JP4704559B2 - Manufacturing method of basic water-absorbing resin, manufacturing method of water-absorbing agent, and use thereof - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、塩基性吸水性樹脂の製法、吸水剤の製法、ならびにその使用に関するものである。
【０００２】
更に詳しくは、加圧下の吸水倍率が著しく向上した吸水剤の製法およびその主成分となる塩基性吸水性樹脂の製法に関するものである。
【０００３】
【従来の技術】
近年、紙オムツや生理用ナプキン、いわゆる失禁パット等の衛生材料には、その構成材として、体液を吸収させることを目的とし、いわゆる吸水性樹脂が幅広く使用されている。
【０００４】
上記の吸水性樹脂としては、例えば、ポリアクリル酸部分中和物架橋体、澱粉−アクリル酸グラフト重合体の加水分解物、酢酸ビニル−アクリル酸エステル共重合体ケン化物、アクリロニトリル共重合体若しくはアクリルアミド共重合体の加水分解物又はこれらの架橋体等が知られている。
しかし、これら従来知られている吸水性樹脂のほとんどその全てが酸性吸水性樹脂の酸性基をアルカリ金属化合物等で中和したものである。このため、その粒子表面近傍を２次架橋処理していない場合にはその生理食塩水に対する加圧下の吸収倍率は１０ｇ／ｇ未満であり、たとえその粒子表面近傍が２次架橋処理されたものであったとしても人工尿に対する加圧下の吸収倍率は高々３０ｇ／ｇで、紙おむつや生理用品に用いられるには依然として不十分であり、加圧下条件であっても人工尿をたくさん吸収し膨潤できる新しい吸水剤が嘱望されていた。
このような問題点を解決するためにＷＯ９６／１５１８０号公報、ＷＯ９６／１７６８１号公報、ＷＯ９８／２４８３２号公報、ＷＯ９８／３７１４９号公報、ＷＯ９９／３４８４１号公報、ＷＯ９９／３４８４２号公報、ＷＯ９９／３４８４３号公報、ＷＯ９９／２５３９３号公報、ＷＯ９９／３０７５１号公報等では、酸性吸水性樹脂と塩基性吸水性樹脂とからなる吸水剤が提案されている。しかしながらこれらの特許に記載の方法では、該吸水剤の主成分となる塩基性吸水性樹脂は、一度塊状ゲル状態を経た後細粒化され、必要により最適粒度に該塩基性吸水性樹脂を粒度調整した後、更に酸性吸水性樹脂と混合されており、大規模生産においては非常に大きな塊状ゲルを取り扱いしなければならず、その設備が大掛かりになるばかりでなく、生産性が非常に低く、またバッチごとの品質が安定しないものとならざるを得なかった。特に、一度塊状ゲルを形成した後、該含水ゲルを機械的に細分化する場合には、一度架橋により形成されたネットワークを切断せねばならず、その場合に可溶性成分が増加したり、架橋構造が不均一になったり、細分化に多大なエネルギーを要するといった問題点もかかえていた。また、ＥＰ９４９２９０Ａ２公報では、塩基性樹脂を懸濁液の状態で架橋反応を行う方法が提案されているが、有機溶剤を用いることから、その有機溶剤を除去する工程が必要であり、生産設備が大掛かりになるばかりでなく、生産性が非常に低くなっていた。また、このようにして得られた塩基性吸水性樹脂は略球状となり、不定形状粒子は得られない。
【０００５】
【発明が解決しようとする課題】
本発明は、上記従来の問題点に鑑みなされたものであり、その目的は、加圧下の吸水倍率に優れた吸水剤の主成分となる塩基性吸水性樹脂を、１）好ましくはワンステップで、２）小さい設備で、３）安価に、４）安定的に高品質のものを、５）生産性よく製造する方法を提供することにある。また別の目的は、加圧下の吸水倍率に優れた吸水剤を、１）小さい設備で、２）安価に、３）安定的に高品質のものを、４）生産性よく製造する方法を提供することにある。更に、本発明の方法で得られた吸水剤をおむつなどの吸収物品の構成要素として使用した場合には、長時間使用した場合であっても漏れを著しく低減でき、表面をサラサラの乾いた状態に保つことができる。また、本発明の方法で得られた吸水剤はアンモニア、アセトアルデヒドやメルカプタンなどを消臭する効果に優れた消臭製品の構成要素としても使用することが可能である。
【０００６】
【課題を解決するための手段】
本願発明者等は、上記目的を達成できる新規な塩基性吸水性樹脂の製法、吸水剤の製法について鋭意検討した結果、本発明に到達した。
すなわち本発明は、水溶性のアミノ基含有塩基性樹脂と架橋剤を反応させて純水の吸水倍率が１ｇ／ｇ以上の塩基性吸水性樹脂を得る際に、架橋反応の進行と同時に得られるゲル状の反応物の粒子状への細分化を行なうことを特徴とする不定形状の塩基性吸水性樹脂の製法である。
本発明にかかる吸水剤の製法は、上記方法で得られた塩基性吸水性樹脂に酸性吸水性樹脂を混合する方法である。
本発明にかかる別の吸水剤の製法は、上記方法で架橋反応と細分化を行う際に、酸性吸水性樹脂を共存させることにより、塩基性吸水性樹脂と酸性吸水性樹脂との混合物を得る方法である。
【０００７】
【発明の実施の形態】
以下に本発明について詳細に説明する。
【０００８】
本発明において、塩基性吸水性樹脂とは、純水中で塩基性を示し且つ純水を吸収し膨潤することのできる範囲まで架橋されている塩基性吸水性樹脂である。本発明において水中で塩基性を示す塩基性吸水性樹脂は、例えば純水中でのｐＨが８よりも大きい値を示し、且つ純水の吸収倍率が１ｇ／ｇ以上であることが好ましい。このような物性値を示す塩基性吸水性樹脂としては、例えば塩基性基を含み、その塩基性基の５０％〜１００モル％が未中和（フリー）の塩基の形で存在し水不溶性となるまでゆるく架橋された塩基性樹脂を挙げることができる。より好ましくはその塩基性基の７０〜１００モル％が未中和（フリー）の塩基の形で存在し、最も好ましくはその塩基性基の９０〜１００モル％が未中和（フリー）の塩基の形で存在し且つ水不溶性になるまでゆるく架橋された塩基性樹脂である。本発明でより好ましく使用される塩基性吸水性樹脂は、１〜４級のアミノ基（アミン基）を含有し、そのアミノ基（アミン基）の５０％〜１００モル％が未中和（フリー）の塩基の形で存在するアミノ基含有塩基性樹脂を、水不溶性且つ水膨潤性となるまで架橋剤によりゆるく架橋した塩基性吸水性樹脂を例示できる。
【０００９】
本発明において使用される塩基性樹脂としては、実質的に架橋前の状態では水溶性あるいは水分散性の、架橋されていない親水性の塩基性樹脂を例示することができる。このようなものとしては、例えば、直鎖状ポリアルキレンアミン、分岐状ポリアルキレンアミン、ポリビニルアミン、ポリアリルアミン、ポリN−ビニルイミダゾール、ポリビニルピリジン、ポリビニルピリジンアミンオキシド、ポリジアリルアミン、ポリアミドポリアミン、ポリジメチルアミノアルキルアクリレート、ポリジメチルアミノアルキルメタクリレート、ポリジメチルアミノアルキルアクリルアミド、ポリジメチルアミノアルキルメタクリルアミド、ポリアミジン、ポリビニルグアニジン、ポリジアリルアミン、ポリアクリル酸ヒドラジン、アスパラギン酸−ヘキサメチレンジアミン重縮合物；ポリリシンのような塩基性ポリアミノ酸；キトサンなどの天然物由来の塩基性樹脂；およびこれらの重合体の共重合体などを挙げることができる。これらは架橋により塩基性吸水性樹脂に転換し得ることが必須である。好ましくは、塩基性樹脂がアミノ基含有塩基性樹脂であり、より好ましくは該塩基性樹脂が、その塩基性基の９０〜１００モル％が未中和（フリー）の塩基の形で存在する、ポリエチレンイミン、ポリアリルアミン、ポリビニルアミン、ポリジアリルアミン、ポリジアリルジメチルアミンからなる群より選ばれる少なくとも１種であり、最も好ましくはポリエチレンイミン、ポリアリルアミン、ポリビニルアミンより選ばれる少なくとも１種である。また本発明において、架橋前の塩基性樹脂の平均分子量は約１，０００〜１０，０００，０００の範囲であることが好ましい。
【００１０】
本発明では、塩基性吸水性樹脂は、対応する塩基性樹脂をその官能基（例えばアミノ基（アミン基））と反応し共有結合を形成し得る基を２個以上有する架橋剤で架橋し、該樹脂中に架橋構造を導入することで得ることができる。架橋剤としては、その官能基がアミノ基（アミン基）である場合には例えば、エポキシ基、アルデヒド基、ハロゲン化アルキル基、イソシアネート基、カルボキシル基、酸無水物基、酸ハライド基、エステル結合部分、活性二重結合などを１分子あたり２個以上有する、従来一般に用いられている化合物を使用できる。このような架橋剤としては、例えば、ビスエポキシ化合物；エピクロルヒドリン、ジブロムエチレンなどのジハロゲン化物；ホルマリン、グリオキザールのようなジアルデヒド化合物；（ポリ）エチレングリコール類のジグリジシルエーテル、（ポリ）プロピレングリコール類のジグリシジルエーテル、ネオペンチルアルコールなどのジアルコールのジグリシジルエーテル類、グリセロールのポリグリシジルエーテル類；メチルアクリレート、エチルアクリレートなどのα，β−不飽和カルボン酸エステル類；メチレンビスアクリルアミドなどのジ−α，β−不飽和カルボニル化合物；α，ω−アルキレンジイソシアネート類などが挙げられるが、これらに限定されるものではない。架橋剤の種類および量は、得られる塩基性吸水性樹脂の吸水倍率、強度などを考慮しつつ選択されるが、塩基性樹脂がアミノ基含有塩基性樹脂である場合には、高分子のアミンユニットに対し０．００１〜２０モル％の範囲が好ましい。架橋剤量が０．００１モル％よりも少ない場合には得られる塩基性吸水性樹脂の吸水倍率が低くまた強度が不十分となり、２０モル％を超える場合には吸水倍率が大きく低下することがある。
【００１１】
本発明の塩基性吸水性樹脂の製法は、塩基性樹脂と架橋剤にせん断力を加え、架橋反応の進行と同時に細分化を行なうことを特徴とする。本発明で言うところの細分化とは、架橋により生成するゲルが流動性を有する粒子状の大きさに細かく砕かれることを言う。塩基性樹脂と架橋剤にせん断力が加わることにより、塩基性樹脂と架橋剤が接触し、塩基性樹脂は架橋剤により架橋されることになるが、その際に引き続きせん断力が加わることによって、架橋反応の進行と同時に得られるゲル状の塩基性吸水性樹脂に均一な架橋構造が導入され、同時に粒子状に細分化されることになる。架橋反応の進行と同時に細分化が行われることにより、個々に生成する塩基性吸水性樹脂粒子内の架橋密度分布がより均質となり、その結果、粒子サイズが揃うと同時に、吸水倍率に優れ、可溶性成分の少ないという特徴を有する塩基性吸水性樹脂粒子を生産性良く製造することができる。これは塊状ゲル生成後に細分化するという従来の方法では成し得なかった特徴であり、架橋反応の進行と同時に細分化されることで、本発明の吸水剤に最も適した塩基性吸水性樹脂を得ることができる。架橋反応の進行と同時に細分化するに先立ち、塩基性樹脂と架橋剤はそれぞれ、溶液により希釈された状態で、或いは無希釈の液体の状態で供給されても良い。
【００１２】
本発明において、塩基性樹脂および架橋剤は、それぞれ、溶液の状態或いは液体の状態で予め混合された後、供給されても良い。溶液状態で混合される場合の媒体としては水性液が好適に使用される。塩基性樹脂と架橋剤の混合状態での合計濃度は、４０重量％以上の濃度の水性液の状態が好ましく、更に好ましくは８０重量％以上の水性液濃度である。適切な架橋密度分布および粒子制御をするための最も好ましい形態は双方が無希釈の液体状態で予め混合されることである。可能な限り両者が高濃度の状態（例えば双方が無希釈の状態）で前もって混合されることは、生産性良く、均質な架橋密度分布を有する塩基性吸水性樹脂が得られるのでより好ましい。両者の混合は、乱流が発生する状況下に両者が接触するのであれば、特に混合機を使用しなくても良く、また下記に例示される容器内で両者が混合されてもよい。好ましくは、積極的に乱流を発生させる装置を具備したラインミルのような管内流体混合機内で両者が混合される。管内流体混合機としては例えば、静止型管内混合装置や液体せん断機構を備えた混合装置など従来公知の装置を例示できる。静止型管内混合装置としては、例えば、ノリタケスタティックミキサー（（株）ノリタケカンパニーリミティッド）、スルーザーミキサー（住友重機械工業（株））、東レ静止型管内混合機（東レ（株））、スケヤミキサー（（株）桜製作所）、ＴＫ−ＲＯＳＳ−ＬＰＤミキサー（特殊機化工業（株））などを挙げることができ、液体せん断機構を備えた混合装置としては、ホモミキサーやホモジナイザー等を挙げることができる。
【００１３】
本発明において、塩基性樹脂と架橋剤は、せん断力が加えられ、架橋反応の進行と同時に細分化されて本発明の塩基性吸水性樹脂となる。また別の実施形態では、塩基性樹脂と架橋剤は、容器内でせん断力により架橋反応の進行と同時に細分化され、更に非連続に容器外に排出されて本発明の塩基性吸水性樹脂となる。更にまた別の実施形態では、塩基性樹脂と架橋剤は回転攪拌軸を有する容器内に連続的に供給され、該攪拌軸によるせん断力により架橋反応の進行と同時に細分化を行なわれ、更に容器外に連続的に排出されて本発明の塩基性吸水性樹脂となる。せん断力を加え、架橋反応の進行と同時に細分化することのできる反応容器としては、例えば、円筒型混合機、タービュライザー、ナウター型混合機、Ｖ型混合機、パドルドライヤー、押し出し機、双腕型ニーダー、バンバリーミキサー、スクリュー型混合機、万能混合機、2軸押し出し機、回転式混合機、ロールミキサーなどの従来公知の容器を例示できる。塩基性樹脂と架橋剤を、容器内でせん断力により架橋反応の進行と同時に細分化を行ない、更に非連続に容器外に排出することの出来る反応容器としては、例えば、円筒型混合機、ナウター型混合機、Ｖ型混合機、双腕型ニーダー、バンバリーミキサー、万能混合機などを例示でき、好ましくは例えば双腕型ニーダーを例示できる。塩基性樹脂と架橋剤を回転攪拌軸を有する容器内に連続的に供給し、該攪拌軸によるせん断力により架橋反応の進行と同時に細分化を行ない、更に容器外に連続的に排出することのできる反応容器としては例えば、ＫＲＣニーダー、タービュライザー、パドルドライヤー、押し出し機、スクリュー型混合機、2軸押し出し機、コンティニアスニーダーなどを例示できる。また、架橋反応の際の温度・反応時間は、使用される塩基性樹脂と架橋剤の組合せにもよるが、通常は、室温〜１５０℃の温度で数秒〜数時間の範囲である。好ましくは５０℃〜１２０℃の温度下で数秒〜１時間の範囲であり、特に操作を連続的に行なう場合には、容器内での滞留時間内に架橋反応を終えることが好ましく、容器をコンパクトにするためには反応を５０℃〜１２０℃の温度下で数秒〜５０分の範囲で終えるような条件を選択することが好ましい。また、反応は減圧下、常圧下、加圧下のいずれの状態で行なっても良い。更に溶媒として水性液を使用する場合には、架橋反応の進行と同時に細分化しながら、同時に水性液を除去しつつ、反応を行なうことも可能である。
【００１４】
本発明において、このようにして得られた塩基性吸水性樹脂は、必要により、更に整粒工程、或いは水洗工程および／または乾燥工程を経て、所望の塩基性吸水性樹脂とすることができる。また、攪拌軸の回転速度、攪拌翼の形状をコントロールすることによって、得られる塩基性吸水性樹脂の細分化の程度および粒子サイズを制御することも可能である。
【００１５】
このようにして得られた本発明の塩基性吸水性樹脂は、例えば、不定形状であり、粒子サイズは全体の少なくとも８０重量％以上の粒子が粒径１０〜１０００μｍの範囲であり、水可溶性成分量は１０重量％未満、吸水倍率は１〜１００ｇ／ｇの範囲である。このような物性を有する本発明の塩基性吸水性樹脂は、更に酸性吸水性樹脂と混合されることで、加圧下の吸水倍率に優れた本発明の吸水剤とすることができる。特に、酸性吸水性樹脂と混合され吸水剤として使用されるには、塩基性吸水性樹脂の平均粒子サイズが１００〜８５０μｍ（好ましくは２００〜３００μｍ）であり、可溶性成分量は５重量％未満、吸水倍率が５〜２０ｇ／ｇの範囲に制御されることが好ましい。
【００１６】
本発明において、酸性吸水性樹脂とは、純水中で酸性を示し且つ純水を吸収し膨潤することのできる範囲まで架橋されている酸性吸水性樹脂である。本発明において水中で酸性を示す酸性吸水性樹脂は、例えば純水中でのｐＨが６よりも小さい値を示し、且つ純水の吸水倍率が１ｇ／ｇ以上であることが好ましい（さらに好ましくは、純水の吸水倍率が１０ｇ／ｇ以上）。このような物性値を示す酸性吸水性樹脂としては、例えば酸性基を含み、その酸性基の５０％〜１００モル％が未中和（フリー）の酸の形で存在し水不溶性となるまでゆるく架橋された酸性樹脂を挙げることができる。より好ましくはその酸性基の７０〜１００モル％が未中和（フリー）の酸の形で存在し、最も好ましくはその酸性基の９０〜１００モル％が未中和（フリー）の酸の形で存在し且つ水不溶性になるまでゆるく架橋された酸性樹脂である。本発明でより好ましく使用される酸性吸水性樹脂は、例えば、カルボン酸基、スルホン酸基およびリン酸基からなる群より選ばれる少なくとも１種の酸基を含有する酸性吸水性樹脂を挙げることができる。本発明において、酸性吸水性樹脂は例えば、イ）酸基を含有する重合性単量体を共重合性架橋剤の存在下に重合する方法、ロ）酸基を含有する重合性単量体を重合して得られた酸基含有重合体に後架橋処理を施す方法などの従来公知の方法により得ることができる。また本発明で用いることのできる酸性吸水性樹脂はポリアスパラギン酸架橋体、ポリグルタミン酸架橋体のような架橋ポリペプチドやカルボキシメチルセルロース架橋体のような天然物由来の酸性吸水性樹脂であってもよい。
【００１７】
酸基含有重合体の後架橋処理は、例えば、I）加熱処理により架橋構造を導入する方法、II）電子線、ガンマー線などの放射線照射により架橋構造を導入する方法、III）ポリエチレングリコールジグリシジルエーテル、グリセロールジグリシジルエーテル、エチレングリコール、ポリエチレングリコール、プロピレングリコール、グリセリン、ペンタエリスリトール、エチレンジアミン、ポリエチレンイミン、エチレンカーボネートなどの酸基含有重合体の官能基と反応し得る官能基を１分子中に２個以上有する化合物により重合体に架橋構造を導入する方法などにより達成することができる。
【００１８】
本発明においてより好適に採用される酸性吸水性樹脂の製法は、その重合度および架橋度のコントロールの容易さから、イ）の酸基を含有する重合性単量体を共重合性架橋剤の存在下に重合する方法である。
【００１９】
本発明で好適に使用できる酸基を含有する重合性単量体としては例えば、アクリル酸、メタアクリル酸、エタアクリル酸、クロトン酸、ソルビン酸、マレイン酸、イタコン酸、けい皮酸、それらの無水物などのカルボン酸基を含有する重合性単量体； ビニルスルホン酸、アリルスルホン酸、スチレンスルホン酸、ビニルトルエンスルホン酸、２−（メタ）アクリルアミド−２−メチルプロパンスルホン酸、２−（メタ）アクリロイルエタンスルホン酸、２−（メタ）アクリロイルプロパンスルホン酸などのスルホン酸基を含有する重合性単量体；２−ヒドロキシエチルアクリロイルホスフェート、２−ヒドロキシエチルメタクリロイルホスフェート、フェニル−２−アクリロイロキシエチルホスフェート、ビニルリン酸などのリン酸基を含有する重合性単量体等を挙げることができる。
【００２０】
これらのうちで好ましいものはカルボン酸基またはスルホン酸基を含有する重合性単量体であり、特に好ましいものはカルボン酸基を含有する重合性単量体であり、最も好ましくはアクリル酸である。これらの酸基を含有する単量体は単独で使用してもよく、また２種以上を併用してもよい。
【００２１】
本発明において、前記酸基を含有する単量体と共に必要により他の重合性単量体を使用することができる。このようなものとしては例えばメチル(メタ)アクリレート、エチル(メタ)アクリレート、メトキシポリエチレングリコール（メタ）アクリレート、ポリエチレングリコールモノ（メタ）アクリレートなどの不飽和カルボン酸（アクリル酸、メタアクリル酸、エタアクリル酸、クロトン酸、ソルビン酸、マレイン酸、イタコン酸、けい皮酸など）のアルキルまたはアルキレンオキシドエステル類；スチレンなどの芳香族ビニル炭化水素；エチレン、プロピレン、ブテンなどの脂肪族ビニル炭化水素；アクリロニトリルなどの不飽和ニトリル類；アクリルアミド、メタアクリルアミドなどの不飽和アミド類などが挙げられる。
【００２２】
本発明において好適に使用できる酸基を含有する単量体と共重合できる共重合性架橋剤としては、少なくとも２個の重合性二重結合を有する化合物（１）および少なくとも１個の重合性二重結合を有しかつ単量体と反応性の官能基を少なくとも１個有する化合物（２）が挙げられる。
【００２３】
化合物（１）の具体例としては以下のものが挙げられる。例えば、Ｎ，Ｎ′−メチレンビス（メタ）アクリルアミド、（ポリ）エチレングリコールジ（メタ）アクリレート、（ポリ）プロピレングリコールジ（メタ）アクリレート、トリメチロールプロパントリ（メタ）アクリレート、トリメチロールプロパンジ（メタ）アクリレート、グリセリントリ（メタ）アクリレート、グリセリンアクリレートメタクリレート、エチレンオキサイド変性トリメチロールプロパントリ（メタ）アクリレート、ペンタエリスリト−ルテトラ（メタ）アクリレ−ト、ジペンタエリスリトールヘキサ（メタ）アクリレート、トリアリルシアヌレート、トリアリルイソシアヌレート、トリアリルホスフェート、トリアリルアミン、ポリ（メタ）アリロキシアルカン、ジビニルベンゼン、ジビニルトルエン、ジビニルキシレン、ジビニルナフタレン、ジビニルエーテル、ジビニルケトン、トリビニルベンゼン、トリレンジイソシアネート、ヘキサメチレンジイソシアネートなど。
【００２４】
化合物（２）の例としては、たとえばグリシジル（メタ）アクリレートのような一分子中にエポキシ基と重合性二重結合を有する化合物；N−メチロール（メタ）アクリルアミドのような一分子中にヒドロキシ基と重合性二重結合を有する化合物；Ｎ，Ｎ，Ｎ−トリメチル−Ｎ−（メタ）アクリロイオキシエチルトリメチルアンモニウムクロライド、Ｎ，Ｎ，Ｎ−トリエチル−Ｎ−（メタ）アクリロイオキシエチルトリメチルアンモニウムクロライド、（メタ）アクリル酸ジメチルアミノエチル、（メタ）アクリル酸ジエチルアミノエチル、アリルアミン、ビニルピリジンのような１〜４級アミノ基含有不飽和化合物などを挙げることができる。
【００２５】
共重合性架橋剤のうちで好ましいものは、ビス（メタ）アクリルアミド、ポリオールと不飽和モノカルボン酸とのジ−またはポリ−エステル、ポリアリル化合物であり、特に好ましいものは、Ｎ，Ｎ′−メチレンビスアクリルアミド、トリメチロールプロパントリ（メタ）アクリレート、（ポリ）エチレングリコールジアクリレート、トリアリルアミン、ポリ（メタ）アリロキシアルカンより選ばれる少なくとも１種である。
【００２６】
本発明において共重合性架橋剤の量は全重合性単量体および共重合性架橋剤の合計重量にもとづいて通常０．００１〜１０％、好ましくは０．０１〜５％である。共重合性架橋剤の量が０．００１％未満では得られた酸性吸水性樹脂は吸水時のゲル強度が小さくなることがあり、１０％を越えると吸水倍率が低くなることがあるため好ましくない。
【００２７】
必要により使用される他の重合性単量体の量は全重合性単量体および共重合性架橋剤の合計重量に基づいて通常４０％以下、好ましくは２０％以下である。
【００２８】
なお重合に際しては、澱粉やセルロ−ス、澱粉やセルロ−スの誘導体、ポリビニルアルコ−ル、ポリアクリル酸、ポリアクリル酸架橋体等の親水性高分子、次亜リン酸（塩）等の連鎖移動剤や、水溶性ないし水分散性界面活性剤を添加してもよい。なお、これら重合性単量体に加える化合物は、米国特許４０７６６６３号，同４３２００４０号，同４８３３２２２号，同５１１８７１９号，同５１４９７５０号，同５１５４７１３号および同５２６４４９５号や、欧州特許０３７２９８１号および同０４９６５９４号などに例示されている。
【００２９】
本発明において、酸基含有単量体の重合方法、または酸基含有単量体および共重合性架橋剤および必要により使用されるその他の重合性単量体の重合方法は、例えば、バルク重合や沈澱重合を採用することも可能であるが、性能面や重合の制御の容易さから、単量体を水溶液として、水溶液重合、逆相懸濁重合を行うことが好ましい。またこの場合の溶媒として、例えば水、メタノール、エタノール、アセトン、Ｎ，Ｎ−ジメチルホルムアミド、ジメチルスルホキシド、メチルエチルケトン、およびこれらの２種以上の混合物を使用してもよい。溶媒を使用した場合の酸基含有単量体の濃度には特に限定はないが、重量基準で通常１０％以上、好ましくは１５〜８０％である。また重合温度については通常０℃〜１５０℃、好ましくは１０〜１００℃の範囲である。
【００３０】
また重合を開始する方法としては、従来から知られている方法で良く、例えばラジカル重合触媒を用いて重合させる方法、および放射線、電子線、紫外線などを照射する方法を挙げることができる。
【００３１】
ラジカル重合触媒を用いる方法において、この触媒としては、過硫酸カリウム、過硫酸アンモニウム、過硫酸ナトリウムなどの無機過酸化物；ｔ−ブチルハイドロパーオキサイド、過酸化水素、過酸化ベンゾイル、クメンヒドロパーオキサイドなどの有機過酸化物；２，２′−アゾビス（２−アミジノプロパン）二塩酸塩、アゾイソブチロニトリル、アゾビスシアノ吉草酸等のアゾ化合物を挙げることができる。過酸化物のような酸化性ラジカル重合触媒を用いる場合、亜硫酸ナトリウム、亜硫酸水素ナトリウム、硫酸第一鉄、Ｌ−アスコルビン酸等の還元剤を併用してレドックス重合としても良い。またこれらラジカル重合触媒の複数種を併用して用いてもよい。ラジカル重合触媒の使用量も通常で良く、例えば全重合性単量体および共重合性架橋剤の合計重量に基づいて通常０．０００５〜５％、好ましくは０．０００１〜１％である。
【００３２】
本発明において、上記方法で得られる酸性吸水性樹脂は、必要により、従来公知の乾燥・粉砕・分級工程を経て、実質上乾燥した粉末の状態で使用される。好ましくは、該酸性吸水性樹脂は、その含水率が２０重量％未満の、粒子サイズが１０〜１０００μｍの範囲の粉末の状態で、前記塩基性吸水性樹脂と混合され本発明の吸水剤とすることができる。酸性吸水性樹脂の含水率が２０重量％以上の場合には、塩基性吸水性樹脂との混合条件によっては得られる吸水剤における脱塩効果の低下が起こることがあるので注意を要する。
本発明の吸水剤の製法は、塩基性樹脂と架橋剤を架橋反応の進行と同時に細分化を行ない得られる塩基性吸水性樹脂と、酸性吸水性樹脂とを混合する方法である。この製法の具体例としては、たとえば、以下の（ａ）および（ｂ）の方法を挙げることができる。
（ａ）塩基性樹脂と架橋剤を架橋反応の進行と同時に反応物の細分化を行ない得られる塩基性吸水性樹脂と、酸性吸水性樹脂とを予め別々に用意した後、両者を混合する。
（ｂ）塩基性樹脂と架橋剤との架橋反応の進行と同時に反応物の細分化を行う際に、酸性吸水性樹脂を共存させることにより、塩基性樹脂の架橋反応の進行と同時に細分化および酸性吸水性樹脂との混合を行う。
上記方法（ａ）において、塩基性吸水性樹脂と酸性吸水性樹脂との混合比率はその使用目的や被吸収液の種類によっても異なるが、重量比（固形分として）で９５：５〜５：９５の範囲が好ましく、より好ましくは９０：１０〜１０：９０の範囲である。また塩基性吸水性樹脂と酸性吸水性樹脂との混合は、両者が混合できるのであればその混合機は特に限定されないが、そのような混合装置としては、例えば、円筒型回転混合機、二重壁円錐型混合機、Ｖ字型混合機、リボン型混合機、スクリュー型混合機、流動型炉ロータリーデスク型混合機、気流型混合機、双腕型ニーダー、内部混合機、回転式混合機、せん断型混合機、タービュライザー、万能混合機、ナウター型混合機、流動層式混合機等の従来から知られている混合機を例示できる。また混合前に塩基性吸水性樹脂と酸性吸水性樹脂はそれぞれの粒子が表面架橋処理を施されたものであっても良い。
上記方法（ｂ）において、塩基性樹脂と架橋剤としては、前述で説明した塩基性樹脂と架橋剤が使用されるが、塩基性樹脂は、好ましくはその塩基性基の５０％〜１００モル％が未中和（フリー）の塩基の形で存在し、より好ましくはその塩基性基の７０〜１００モル％が未中和（フリー）の塩基の形で存在し、最も好ましくはその塩基性基の９０〜１００モル％が未中和（フリー）の塩基の形で存在する。また、使用される塩基性樹脂の濃度は、好ましくは５０重量％以上であり、さらに好ましくは８０重量％以上であり、最も好ましくは９８重量％以上である。
上記方法（ｂ）で使用される架橋剤の量は、塩基性樹脂がアミノ基含有塩基性樹脂である場合には、高分子のアミンユニットに対し０．００１〜２０モル％の範囲が好ましい。また、塩基性樹脂と酸性吸水性樹脂との混合比率は、重量比（固形分として）で９０：１０〜１０：９０の範囲が好ましく、より好ましくは８０：２０〜２０：８０の範囲、最も好ましくは７０：３０〜３０：７０の範囲である。
上記方法（ｂ）で使用される酸性吸水性樹脂の含水率は、２０重量％未満が好ましい。
塩基性樹脂と架橋剤と酸性吸水性樹脂の混合は、三者が混合できるのであればその混合機は特に限定されないが、そのような混合装置としては、例えば、ＫＲＣニーダー、タービュライザー、パドルドライヤー、押し出し機、スクリュー型混合機、2軸押し出し機、コンティニアスニーダーなどを例示できる。また、架橋反応の際の温度・反応時間は、通常は、室温〜１５０℃の温度で数秒〜数時間の範囲である。好ましくは５０℃〜１２０℃の温度下で数秒〜１時間の範囲であり、特に操作を連続的に行なう場合には、容器内での滞留時間内に架橋反応を終えることが好ましく、容器をコンパクトにするためには反応を５０℃〜１２０℃の温度下で数秒〜５０分の範囲で終えるような条件を選択することが好ましい。また、反応は減圧下、常圧下、加圧下のいずれの状態で行なっても良い。
上記方法（ｂ）は、方法（ａ）と比較して、塩基性樹脂と架橋剤の架橋反応で得られる塩基性吸水性樹脂を単離しないので、吸水剤をワンステップでより生産性良く製造できる。
このようにして本発明の製法で得られた吸水剤は、必要により乾燥され、粉砕されて所望の粒度の吸水剤とすることができる。乾燥する場合の乾燥温度は例えば５０〜２００℃の範囲であり、場合によっては窒素等の不活性ガス雰囲気下で乾燥してもよい。乾燥機としては、例えば、熱風乾燥機、回転式乾燥機、パドルドライヤー、円盤型乾燥機、ベルト式乾燥機、Jナウター型乾燥機、高周波乾燥機、減圧乾燥機、凍結乾燥機、溝型混合乾燥機、ロータリー乾燥機、ディスク乾燥機、流動層式乾燥機、気流型乾燥機、赤外線乾燥機等が挙げられる。また、粉砕方法についても特に限定はなく、ハンマー式粉砕機、衝撃式粉砕機、ロール式粉砕機、ジェット気流式粉砕機など通常の装置が使用できる。
本発明の製法で得られた吸水剤の加圧下の吸水倍率（測定開始から１時間後）は、好ましくは２０ｇ／ｇ以上、さらに好ましくは３０ｇ／ｇ以上、最も好ましくは３５ｇ／ｇ以上である。また、吸水剤の加圧下の吸水倍率（測定開始から４時間後）は、好ましくは２５ｇ／ｇ以上、さらに好ましくは３５ｇ／ｇ以上、最も好ましくは４０ｇ／ｇ以上である。
本発明の製法で得られた吸水剤の平均粒子サイズは好ましくは１０〜１０００μm、さらに好ましくは、１００〜８５０μm 、最も好ましくは、２００〜６００μmである。
また、本発明では、さらに消毒剤、消臭剤、抗菌剤、香料、各種の無機粉末、有機粉末、発泡剤、顔料、染料、親水性繊維、フィラー、疎水性繊維、肥料等を混練時に添加し、これにより、本発明の製法で得られた吸水剤に種々の機能を付与させることもできる。
本発明の製法で得られた吸水剤は、各種の吸収性物品、特に、薄型化の進む紙オムツや生理用ナプキン、失禁パット等の吸収体に特に好適に用いることができ、長時間使用した場合であっても漏れを著しく低減でき、表面をサラサラの乾いた状態に保つことができる吸収性物品を提供できる。
【００３３】
本発明の製法で得られた吸水剤は、塩水をすばやく吸収できるので、各種の吸収性物品；紙オムツや生理用ナプキン、失禁パット等の吸水剤、ワイパーの吸水剤などの衛生材料分野；鮮度保持剤、肉類・魚介類のドリップ吸収剤などの食品分野；植物や土壌の保水剤、法面緑化用保水剤などの農園芸分野；塗料添加剤、結露防止剤などの建材分野；光ケーブル用止水剤、海底ケーブル用止水剤などの通信分野；印刷フィルムの表面コート剤などの情報分野；含水物凝固剤などの産業用分野；使い捨てカイロ、塩化カルシウムを主剤とした乾燥剤などの家庭用品分野；土木用シーリング剤、コンクリート混和剤などの土木分野など広範囲の分野に好適に用いることができる。
【００３４】
更に本発明の製法で得られた吸水剤は、それ単独でアンモニア、アセトアルデヒドやメルカプタン等の不快な臭い物質を除去できる効果も有しており、消臭製品の構成要素として有効である。
【００３５】
【実施例】
以下、実施例および比較例により、本発明をさらに詳細に説明するが、本発明はこれらにより何ら限定されるものではない。尚、塩基性吸水性樹脂中の可溶性成分量、塩基性吸水性樹脂の吸水倍率、吸水剤の加圧下の吸水倍率、酸性吸水性樹脂の含水率は以下の方法で測定した。また、以下において、単に「部」、「％」とあるのは特にことわりがない限り、それぞれ「重量部」、「重量％」を表すものとする。
【００３６】
（ａ）塩基性吸水性樹脂の可溶性成分量
固形分として１ｇに相当する量の塩基性吸水性樹脂（Ｗａ[ｇ]）を０．０００１ｇまで正確に計って２００ｇの純水に投入し１６時間攪拌した後、その混合溶液を濾紙（ＡＤＶＡＮＴＥＣ社製、Ｎｏ．２）で濾過し、濾液を分取した。２００ｍｌのビーカーに溶解したアミン成分が１〜３ｍｇに相当する量の濾液を採取し（Ｗｂ[ｇ]）、純水を加えて５０ｇにし、更にそこに、０．１mol/l塩酸を添加しｐＨが１〜２になるように調製した。その溶液にトルイジンブルーを数滴添加した後、１／４００ｍｏｌ／ｌポリビニル硫酸カリウム溶液（ＰＶＳＫ、コロイド滴定用）を滴下し、溶液の色が青から赤紫になったところを終点（Ｔ[ｍｌ]）とした。塩基性吸水性樹脂の可溶性成分量の計算は以下の式により求めた。
【００３７】
【数１】
（ｂ）塩基性吸水性樹脂および酸性吸水性樹脂の吸水倍率
固形分として０．２ｇに相当する量の塩基性吸水性樹脂（または酸性吸水性樹脂）を０．０００１ｇまで正確に計って不織布製の袋（６０ｍｍ×６０ｍｍ）に入れ、１００ｇの純水に浸漬した。２４時間後に袋を引き上げ、遠心分離機を用いて２５０Ｇ(２５０×９．８１ｍ／ｓ 2 ）で３分間水切りを行った後、袋の重量Ｗｃ（ｇ）を測定した。また、同様の操作を塩基性吸水性樹脂（または酸性吸水性樹脂）を用いないで行い、その時の重量Ｗｄ（ｇ）を測定した。そして、これら重量Ｗｃ、Ｗｄから、次式、
吸水倍率（ｇ／ｇ）＝（Ｗｃ−Ｗｄ）／０．２−１
に従って塩基性吸水性樹脂（または酸性吸水性樹脂）の吸水倍率（ｇ／ｇ）を算出した。
【００３９】
（ｃ）吸水剤の加圧下の吸水倍率
ステンレス４００メッシュの金網（目の大きさ３８μｍ）を底に融着させた内径６０ｍｍのプラスチックの支持円筒の底の網上に、吸水剤０．９ｇを均一に散布し、その上に吸水剤に対して、４．９ｋＰａの荷重を均一に加えることができるように調整された、外径が６０mmよりわずかに小さく支持円筒との壁面に隙間が生じず、かつ上下の動きは妨げられないピストンと荷重をこの順に載置し、この測定装置一式の重量を測定した（Ｗｅ）。
【００４０】
１５０ｍｍのペトリ皿の内側に直径９０ｍｍのガラスフィルターを置き、塩水（塩化カリウム２．０ｇ、硫酸ナトリウム２．０ｇ、リン酸二水素アンモニウム０．８５ｇ、リン酸水素二アンモニウム０．１５ｇ、塩化カルシウム二水和物０．２５ｇ、塩化マグネシウム六水和物０．５ｇに溶解のための脱イオン水を加え総重量１０００ｇとしたもの）をガラスフィルターの表面と同レベルになるように加える。その上に直径９０ｍｍの濾紙を載せ表面が全て濡れるようにし、かつ過剰の液を除く。
【００４１】
上記測定装置一式を前記湿った濾紙上にのせ、液を荷重下で吸収させる。吸水剤が所定時間液を吸収した後、測定装置一式を持ち上げ、その重量を再測定する（Ｗｆ）。ＷｆよりＷｅを差し引いた値を吸水剤の重量（０．９ｇ）で除して加圧下の吸水倍率（ｇ／ｇ）を求めた。上記測定はピストンと荷重が載ったまま行われ、重量測定後、測定装置一式を前記湿った濾紙上に再度のせ、次の所定時間まで塩水を荷重下で吸水させ、この操作を繰り返して、単位時間後の加圧下の吸水倍率をもとめた。
【００４２】
（ｄ）酸性吸水性樹脂の含水率
酸性吸水性樹脂の初期の重量（Ｗｇ）を予め測定しておき、１８０℃の熱風乾燥機中で３時間乾燥後の重量（Ｗｈ）を測定する。ＷｇよりＷｈを差し引いた値をＷｇで除した値を百分率で表わして、酸性吸水性樹脂の含水率（％）とした。
【００４３】
（参考例１）
アクリル酸１００８．８部、共重合性架橋剤としてＮ，Ｎ′−メチレンビスアクリルアミド８．６３部、および純水３９６０．９部を混合し、窒素ガスで６０分脱気後、開閉可能な密閉容器中に仕込み、窒素雰囲気下で液温を２０℃の温度に保ちながら反応系の窒素置換を続けた。次いで攪拌下に２，２′−アゾビス（２−アミジノプロパン）二塩酸塩の１０重量％水溶液３０．５部、過酸化水素の１０重量％水溶液１０．８部とＬ−アスコルビン酸の１重量％水溶液２５．２部をそれぞれ添加したところ５分後に重合が開始し、３０分後に反応系はピーク温度に達した。重合温度がピークに達した３０分後に、生成した含水ゲル状架橋重合体を取り出し、ミートチョッパーを通過せしめ細分化された含水ゲル状架橋重合体を得た。このものを１３０℃の熱風乾燥機中で１時間乾燥した。乾燥物をロールグラニュレーター（日本グラニュレーター株式会社製）で粉砕し、粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して、酸性吸水性樹脂（１）を得た。なお、この得られた酸性吸水性樹脂（１）の含水率は６％であり、純水に対する吸水倍率は１４ｇ／ｇであった。
【００４４】
（参考例２）
アクリル酸８００部、２−アクリルアミド−２−メチルプロパンスルホン酸の５０重量％水溶液１１５０部、架橋剤としてのＮ，Ｎ′−メチレンビスアクリルアミド５．３５部、および純水２９３０部を混合し、窒素ガスで６０分脱気後、開閉可能な密閉容器中に仕込み、窒素雰囲気下で液温を２０℃の温度に保ちながら反応系の窒素置換を続けた。次いで攪拌下に２，２′−アゾビス（２−アミジノプロパン）二塩酸塩の１０重量％水溶液３０．３部、過酸化水素の３重量％水溶液３３．３部とＬ−アスコルビン酸の０．５重量％水溶液５０部をそれぞれ添加したところ１分後に重合が開始し、１７分後に反応系はピーク温度に達した。重合温度がピークに達した３０分後に、生成した含水ゲル状架橋重合体を取り出し、ミートチョッパーを通過せしめ細分化された含水ゲル状架橋重合体を得た。このものを６０℃の熱風乾燥機中で１時間乾燥した後、更に６０℃の減圧乾燥機にて３時間乾燥せしめた。乾燥物をロールグラニュレーター（日本グラニュレーター株式会社製）で粉砕し、粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して、酸性吸水性樹脂（２）を得た。なお、この得られた酸性吸水性樹脂（２）の含水率は１５％であった。
【００４５】
（実施例１）
７２．７ｇ／分の供給速度で供給される濃度１００％のポリエチレンイミン（商品名：エポミンＳＰ−２００、株式会社日本触媒製）に対し、架橋剤としてのエチレングリコールジグリシジルエーテル（商品名：デナコールＥＸ−８１０、ナガセ化成工業株式会社製、固形分１００％）を７．３ｇ／分の供給速度で供給することにより混合物を連続的に得た。同時に該混合物を回転数５３ｒｐｍで駆動する２軸の回転軸を有する、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）に連続的に投入し、該ＫＲＣニーダー内を連続的に通過させ、せん断力により架橋反応と同時に細分化を行い、本発明の塩基性吸水性樹脂（１）を連続的に得た。この時ジャケット内を通す水の温度は８０℃であった。得られた本発明の塩基性吸水性樹脂（１）の可溶性成分量は３．４％で、吸水倍率は６．５ｇ／ｇで、粒子サイズ１０〜１０００μｍの粒子は９８重量％で、平均粒子サイズは２７０μｍであった。本発明の塩基性吸水性樹脂（１）中の１０〜１０００μｍの粒子は１０００〜８５０μｍの粒子を６％、８５０μｍ〜５００μｍの粒子を１４％、５００μｍ〜３００μｍの粒子を２２％、３００μｍ〜１５０μｍの粒子を４３％、１５０μｍ〜１０μｍの粒子を１５％含んでいた。
【００４６】
（実施例２）
内容量１０リットルでシグマ型攪拌羽根を２本有するジャケット付きステンレス製双腕型ニーダーに蓋をつけた反応容器中に、３０％のポリエチレンイミン（商品名：エポミンＰ−１０００、株式会社日本触媒製）５０００ｇを投入し、回転数４０ｒｐｍで攪拌しながら、Ｎ，Ｎ’−メチレンビスアクリルアミドの９．４％水溶液１５９７ｇ（温度８０℃）を加え、せん断力下に架橋反応と同時に細分化を行った。この時ジャケット温度は６０℃であった。ニーダー中での反応開始から３分後に細分化されたゲルをニーダーから排出し、次いでドームグラン（不二パウダル株式会社製）を通過せしめ、本発明の塩基性吸水性樹脂（２）を得た。得られた本発明の塩基性吸水性樹脂（２）の可溶性成分量は３．１％で、吸水倍率は９．５ｇ／ｇ、乾燥後の粒子サイズ１０〜１０００μｍの粒子は９８重量％で、平均粒子サイズは２１０μｍであった。また、乾燥後の塩基性吸水性樹脂（２）中の１０〜１０００μｍの粒子は、８５０μｍ〜５００μｍの粒子を７％、５００μｍ〜３００μｍの粒子を２２％、３００μｍ〜１５０μｍの粒子を４３％、１５０μｍ〜１０μｍの粒子を２８％含んでいた。
【００４７】
（実施例３）
実施例２のジャケット温度を２５℃とし、ニーダー内での反応時間を１０分間とする以外は実施例２と同様にして、本発明の塩基性吸水性樹脂（３）を得た。得られた本発明の塩基性吸水性樹脂（３）の可溶性成分量は３．４％で、吸水倍率は９．７ｇ／ｇ、乾燥後の粒子サイズ１０〜１０００μｍの粒子は９９重量％で、平均粒子サイズは２３０μｍであった。また、乾燥後の塩基性吸水性樹脂（３）中の１０〜１０００μｍの粒子は、８５０μｍ〜５００μｍの粒子を９％、５００μｍ〜３００μｍの粒子を２５％、３００μｍ〜１５０μｍの粒子を４０％、１５０μｍ〜１０μｍの粒子を２６％含んでいた。
【００４８】
（実施例４）
実施例２において、ドームグランの代わりに、逆戻り防止部材をミートチョッパーケーシング内にらせん状に備えたミートチョッパーを用いた以外は実施例２と同様にして、本発明の塩基性吸水性樹脂（４）を得た。得られた本発明の塩基性吸水性樹脂（４）の可溶性成分量は３．２％で、吸水倍率は９．５ｇ／ｇ、乾燥後の粒子サイズ１０〜１０００μｍの粒子は９３重量％で、平均粒子サイズは１６５μｍであった。また、乾燥後の塩基性吸水性樹脂（４）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を１３％、８５０μｍ〜５００μｍの粒子を７％、５００μｍ〜３００μｍの粒子を９％、３００μｍ〜１５０μｍの粒子を２５％、１５０〜１０μｍの粒子を４６％含んでいた。
【００４９】
（実施例５）
１８２ｇ／分の供給速度で供給される濃度３０％のポリエチレンイミン（商品名：エポミンＰ−１０００、株式会社日本触媒製）に対し、架橋剤としてのＮ，Ｎ’−メチレンビスアクリルアミド（温度８０℃の９．４％水溶液）を５８ｇ／分の供給速度で供給しつつ、両者を回転数５３ｒｐｍで駆動する２軸の回転軸を有する、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）に連続的に投入し、該ＫＲＣニーダー内を連続的に通過させ、せん断力により架橋反応と同時に細分化を行い、本発明の塩基性吸水性樹脂（５）を連続的に得た。この時ジャケット内を通す水の温度は８０℃であった。得られた本発明の塩基性吸水性樹脂（５）の可溶性成分量は３．５％で、吸水倍率は１０．４ｇ／ｇで、乾燥後の粒子サイズ１０〜１０００μｍの粒子は８４重量％で、平均粒子サイズは６５０μｍであった。また、乾燥後の塩基性吸水性樹脂（５）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を３４％、８５０μｍ〜５００μｍの粒子を３１％、５００μｍ〜３００μｍの粒子を２２％、３００μｍ〜１５０μｍの粒子を１１％、１５０〜１０μｍの粒子を２％含んでいた。
【００５０】
（実施例６）
１５７ｇ／分の供給速度で供給される濃度５０％のポリエチレンイミン（商品名：エポミンＰ−１０５０、株式会社日本触媒製）に対し、架橋剤としてのＮ，Ｎ’−メチレンビスアクリルアミド（温度８０℃の９．４％水溶液）を８３ｇ／分の供給速度で供給しつつ、両者を回転数５３ｒｐｍで駆動する２軸の回転軸を有する、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）に連続的に投入し、該ＫＲＣニーダー内を連続的に通過させ、せん断力により架橋反応と同時に細分化を行い、本発明の塩基性吸水性樹脂（６）を連続的に得た。この時ジャケット内を通す水の温度は８０℃であった。得られた本発明の塩基性吸水性樹脂（６）の可溶性成分量は４．７％で、吸水倍率は８．０ｇ／ｇで、乾燥後の粒子サイズ１０〜１０００μｍの粒子は８８重量％で、平均粒子サイズは２９０μｍであった。また、乾燥後の塩基性吸水性樹脂（６）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を２１％、８５０μｍ〜５００μｍの粒子を１２％、５００μｍ〜３００μｍの粒子を１６％、３００μｍ〜１５０μｍの粒子を３５％、１５０〜１０μｍの粒子を１６％含んでいた。
【００５１】
（実施例７）
１５７ｇ／分の供給速度で供給される濃度５０％のポリエチレンイミン（商品名：Ｌｕｐａｓｏｌ−Ｐ、ＢＡＳＦ社製）に対し、架橋剤としてのＮ，Ｎ’−メチレンビスアクリルアミド（温度８０℃の９．４％水溶液）を５８ｇ／分の供給速度で供給しつつ、両者を回転数５３ｒｐｍで駆動する２軸の回転軸を有する、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）に連続的に投入し、該ＫＲＣニーダー内を連続的に通過させ、せん断力により架橋反応と同時に細分化を行い、本発明の塩基性吸水性樹脂（７）を連続的に得た。この時ジャケット内を通す水の温度は８０℃であった。得られた本発明の塩基性吸水性樹脂（７）の可溶性成分量は４．３％で、吸水倍率は７．３ｇ／ｇで、乾燥後の粒子サイズ１０〜１０００μｍの粒子は８８重量％で、平均粒子サイズは３０５μｍであった。また、乾燥後の塩基性吸水性樹脂（７）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を１９％、８５０μｍ〜５００μｍの粒子を１８％、５００μｍ〜３００μｍの粒子を１４％、３００μｍ〜１５０μｍの粒子を２９％、１５０〜１０μｍの粒子を２０％含んでいた。
【００５２】
（実施例８）
実施例１において、架橋剤であるエチレングリコールジグリシジルエーテル（商品名：デナコールＥＸ−８１０、ナガセ化成工業株式会社製）の供給量を５．５ｇ／分にした以外は実施例１と同様にして、本発明の塩基性吸水性樹脂（８）を得た。本発明の塩基性吸水性樹脂（８）の可溶性成分量は４．６％で、吸水倍率は１１．１ｇ／ｇ、粒子サイズ１０〜１０００μｍの粒子は９５重量％で、平均粒子サイズは３１０μｍであった。本発明の塩基性吸水性樹脂（８）中の１０〜１０００μｍの粒子は１０００〜８５０μｍの粒子を８％、８５０μｍ〜５００μｍの粒子を１８％、５００μｍ〜３００μｍの粒子を２７％、３００μｍ〜１５０μｍの粒子を２９％、１５０〜１０μｍの粒子を１８％含んでいた。
【００５３】
（実施例９）
７２．７ｇ／分の供給速度で供給される濃度１００％のポリエチレンイミン（商品名：Ｌｕｐａｓｏｌ−ＷＦ、ＢＡＳＦ社製）に対し、架橋剤としてのエチレングリコールジグリシジルエーテル（商品名：デナコールＥＸ−８１０、ナガセ化成工業株式会社製、固形分１００％）を７．３ｇ／分の供給速度で供給することにより混合物を連続的に得た。同時に該混合物を回転数５３ｒｐｍで駆動する２軸の回転軸を有する、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）に連続的に投入し、該ＫＲＣニーダー内を連続的に通過させ、せん断力により架橋反応と同時に細分化を行い、本発明の塩基性吸水性樹脂（９）を連続的に得た。この時ジャケット内を通す水の温度は８０℃であった。得られた本発明の塩基性吸水性樹脂（９）の可溶性成分量は３．５％で、吸水倍率は５．２ｇ／ｇで、粒子サイズ１０〜１０００μｍの粒子は９８重量％で、平均粒子サイズは２７５μｍであった。本発明の塩基性吸水性樹脂（９）中の１０〜１０００μｍの粒子は１０００〜８５０μｍの粒子を３％、８５０μｍ〜５００μｍの粒子を１６％、５００μｍ〜３００μｍの粒子を２５％、３００μｍ〜１５０μｍの粒子を３８％、１５０μｍ〜１０μｍの粒子を１８％含んでいた。
【００５４】
（実施例１０）
実施例１において、架橋剤であるエチレングリコールジグリシジルエーテルの代わりに、アクリル酸メチル（和光純薬工業株式会社製)を３．７ｇ／分で供給した以外は実施例１と同様にして、本発明の塩基性吸水性樹脂（１０）を得た。本発明の塩基性吸水性樹脂（１０）の可溶性成分量は２．７％で、吸水倍率は２．４ｇ／ｇで、粒子サイズ１０〜１０００μｍの粒子は９９重量％で、平均粒子サイズは２６５μｍであった。本発明の塩基性吸水性樹脂（１０）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を１％、８５０μｍ〜５００μｍの粒子を１７％、５００μｍ〜３００μｍの粒子を２７％、３００μｍ〜１５０μｍの粒子を２８％、１５０〜１０μｍの粒子を２７％含んでいた。
【００５５】
（実施例１１）
実施例１０においてアクリル酸メチルの代わりに、アクリル酸エチル（和光純薬工業株式会社製)を３．７ｇ／分で供給した以外は実施例１０と同様にして、本発明の塩基性吸水性樹脂（１１）を得た。本発明の塩基性吸水性樹脂（１１）の可溶性成分量は３．５％で、吸水倍率は３．４ｇ／ｇで、粒子サイズ１０〜１０００μｍの粒子は９６重量％で、平均粒子サイズは３０５μｍであった。本発明の塩基性吸水性樹脂（１１）中の１０〜１０００μｍの粒子は、１０００〜８５０μｍの粒子を３％、８５０μｍ〜５００μｍの粒子を２０％、５００μｍ〜３００μｍの粒子を２９％、３００μｍ〜１５０μｍの粒子を３３％、１５０〜１０μｍの粒子を１５％含んでいた。
【００５６】
（実施例１２）
実施例１において得られた、塩基性吸水性樹脂（１）４０部と参考例１で得られた酸性吸水性樹脂（１）６０部とシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部をドライブレンドし、本発明の吸水剤（１）を得た。吸水剤（１）は加圧下の吸水倍率が、測定開始から１時間後は３６．７ｇ／ｇで、４時間後は４２．５ｇ／ｇであった。
【００５７】
（実施例１３）
実施例２において得られた、塩基性吸水性樹脂（２）１００部と参考例１で得られた酸性吸水性樹脂（１）３７．５部をニーダー中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、堅型粉砕機（オリエント社製、ＶＭ２７−Ｓ）で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（２）を得た。吸水剤（２）は加圧下の吸水倍率が、測定開始から１時間後は３７．９ｇ／ｇで、４時間後は４３．９ｇ／ｇであった。
【００５８】
（実施例１４）
実施例２において得られた、塩基性吸水性樹脂（２）１００部と参考例２で得られた酸性吸水性樹脂（２）５８．３部をニーダー中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、堅型粉砕機（オリエント社製、ＶＭ２７−Ｓ）で粉砕した。粉砕物を目開き８５０μｍの金網を通過物せしめ、通過物を分取して本発明の吸水剤（３）を得た。吸水剤（３）は加圧下の吸水倍率が、測定開始から１時間後は３９．０ｇ／ｇで、４時間後は４０．５ｇ／ｇであった。
【００５９】
（実施例１５）
実施例１３において、竪型粉砕機で粉砕前に混合していたシリカ微粒子を、８０℃の熱風乾燥前に混合物に添加した以外は実施例１３と同様にして、本発明の吸水剤（４）を得た。吸水剤（４）は加圧下の吸水倍率が、測定開始から１時間後は３５．８ｇ／ｇで、４時間後は４２．７ｇ／ｇであった。
【００６０】
（実施例１６）
実施例１３において、塩基性吸水性樹脂（２）と参考例１で得られた酸性吸水性樹脂（１）の混合をニーダーの代わりに、タービュライザー（ホソカワミクロン株式会社製）を用いた以外は実施例１３と同様にして、本発明の吸水剤（５）を得た。吸水剤（５）は加圧下の吸水倍率が、測定開始から１時間後は３７．６ｇ／ｇで、４時間後は４３．７ｇ／ｇであった。
【００６１】
（実施例１７）
実施例３において得られた塩基性吸水性樹脂（３）を用いて、実施例１３と同様にして、酸性吸水性樹脂（１）と混合後、乾燥、粉砕、分取を行い本発明の吸水剤（６）を得た。吸水剤（６）は加圧下の吸水倍率が、測定開始から１時間後は３６．３ｇ／ｇで、４時間後は４２．６ｇ／ｇであった。
（実施例１８）
実施例４において得られた塩基性吸水性樹脂（４）を用いて、実施例１３と同様にして、酸性吸水性樹脂（１）と混合後、乾燥、粉砕、分取を行い本発明の吸水剤（７）を得た。吸水剤（７）は加圧下の吸水倍率が、測定開始から１時間後は３６．５ｇ／ｇで、４時間後は４３．０ｇ／ｇであった。
【００６２】
（実施例１９）
実施例４において得られた塩基性吸水性樹脂（４）１２０７５部と、参考例１で得られた酸性吸水性樹脂（１）３９３５部とを水張容量が５０Ｌの高速せん断型ミキサ（サイクロミックス、ホソカワミクロン製）中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、堅型粉砕機（オリエント社製、ＶＭ２７−Ｓ）で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（８）を得た。本発明の吸水剤（８）は加圧下の吸水倍率が、測定開始から１時間後は３７．０ｇ／ｇで、４時間後は４３．５ｇ／ｇであった。
【００６３】
（実施例２０）
実施例５で得られた塩基性吸水性樹脂（５）１００部と参考例１で得られた酸性吸水性樹脂（１）３７．５部をニーダー中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、卓上粉砕機で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（９）を得た。本発明の吸水剤（９）は加圧下の吸水倍率が、測定開始から１時間後は３６．７ｇ／ｇで、４時間後は４２．５ｇ／ｇであった。
【００６４】
（実施例２１）
実施例５において得られた塩基性吸水性樹脂（５）１００部と、参考例１で得られた酸性吸水性樹脂（１）３７．５部をニーダー中で攪拌し、両者の混合物を得た。この混合物１００部に対してシリカ微粒子０．２１部を添加し、８０℃の流動層乾燥機（ヤマト科学株式会社製、パルビスミニベットＧＡ２２型）中で１５分間乾燥した後、卓上粉砕機で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（１０）を得た。本発明の吸水剤（１０）は加圧下の吸水倍率が、測定開始から１時間後は３６．５ｇ／ｇで、４時間後は４２．６ｇ／ｇであった。
【００６５】
（実施例２２）
実施例６において得られた本発明の塩基性吸水性樹脂（６）１００部と、参考例１で得られた酸性吸水性樹脂（１）５３．８５部をニーダー中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、卓上粉砕機で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（１１）を得た。本発明の吸水剤（１１）は加圧下の吸水倍率が、測定開始から１時間後は３７．４ｇ／ｇで、４時間後は４４．０ｇ／ｇであった。
【００６６】
（実施例２３）
本発明の塩基性吸水性樹脂（６）１００部の代わりに、実施例７において得られた本発明の塩基性吸水性樹脂（７）を用いて、実施例２２と同様にして酸性吸水性樹脂（１）と混合後、乾燥、粉砕、分取を行い本発明の吸水剤（１２）を得た。本発明の吸水剤（１２）は加圧下の吸水倍率が、測定開始から１時間後は３６．３ｇ／ｇで、４時間後は４２．７ｇ／ｇであった。
【００６７】
（実施例２４）
実施例８において得られた塩基性吸水性樹脂（８）４０部と、参考例１で得られた酸性吸水性樹脂（１）６０部とシリカ微粒子０．３部をドライブレンドし、本発明の吸水剤（１３）を得た。本発明の吸水剤（１３）は加圧下の吸水倍率が、測定開始から１時間後は３０．２ｇ／ｇで、４時間後は３８．３ｇ／ｇであった。
【００６８】
（実施例２５）
実施例９において得られた塩基性吸水性樹脂（９）４０部と、参考例１で得られた酸性吸水性樹脂（１）６０部とシリカ微粒子０．３部をドライブレンドし、本発明の吸水剤（１４）を得た。本発明の吸水剤（１４）は加圧下の吸水倍率が、測定開始から１時間後は３１．５ｇ／ｇで、４時間後は４０．１ｇ／ｇであった。
【００６９】
（実施例２６）
実施例１０において得られた塩基性吸水性樹脂（１０）４０部と、参考例１で得られた酸性吸水性樹脂（１）６０部とシリカ微粒子０．３部をドライブレンドし、本発明の吸水剤（１５）を得た。本発明の吸水剤（１５）は加圧下の吸水倍率が、測定開始から１時間後は３０．７ｇ／ｇで、４時間後は３９．９ｇ／ｇであった。
【００７０】
（実施例２７）
実施例１１において得られた塩基性吸水性樹脂（１１）４０部と、参考例１で得られた酸性吸水性樹脂（１）６０部とシリカ微粒子０．３部をドライブレンドし、本発明の吸水剤（１６）を得た。本発明の吸水剤（１６）は加圧下の吸水倍率が、測定開始から１時間後は３２．１ｇ／ｇで、４時間後は４１．１ｇ／ｇであった。
（比較例１）
１０％に希釈したポリエチレンイミン水溶液（商品名：エポミンＰ−１０００、株式会社日本触媒製、を水で希釈したもの）に対し、エチレングリコールジグリシジルエーテル（商品名：デナコールＥＸ−８１０、ナガセ化成工業株式会社製）を１．５モル％加えて６０℃で１６時間反応させて比較塩基性吸水性樹脂（１）を得た。得られた塊状の比較塩基性吸水性樹脂（１）を予めエクストルーダーを用いて細かく砕き、このもの３７．４部（固形分として）と参考例１で得られた酸性吸水性樹脂（１）５６．１部とを混合し、得られた混合物を更にミートチョッパーを２回通過せしめて両者の混練物を得た。得られた混練物を８０℃の熱風乾燥機中で２時間乾燥し、次いで乾燥物を卓上粉砕機を用いて粉砕し、粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して比較吸水剤（１）を得た。比較吸水剤（１）の加圧下の吸水倍率は測定開始後１時間で１７．５ｇ／ｇ、４時間後で２４．９ｇ／ｇであった。
（実施例２８）
実施例１で得られた本発明の吸水剤（１）の消臭効果を以下の方法で定量化した。５００ｃｃの密閉容器中、アンモニアを１％含有する２０ｇの生理食塩水（０．９％食塩水）に対し、本発明の吸水剤（１）１ｇを添加し、ゲル化せしめた。１時間後の該容器中のヘッドスペースにおけるアンモニア量はブランク（本発明の吸水剤を添加しない場合）の３７％以下に低下していた。５００ｃｃの密閉容器中、アセトアルデヒドを１％含有する２０ｇの生理食塩水（０．９％食塩水）に対し、本発明の吸水剤（１）１ｇを添加し、ゲル化せしめた。１時間後の該容器中のヘッドスペースにおけるアセトアルデヒド量はブランク（本発明の吸水剤を添加しない場合）の１０％以下に低下していた。この結果から、本発明の吸水剤は、アンモニアとアセトアルデヒドの除去効果があることが判明した。
【００７１】
（実施例２９）
Ｎ−ビニルホルムアミド（Ａｌｄｒｉｃｈ製）３５００部および純水１３９００部を混合し、窒素ガスで６０分脱気後、開閉可能な密閉容器中に仕込み、窒素雰囲気下で液温を２０℃の温度に保ちながら反応系の窒素置換を続けた。次いで攪拌下に２，２′−アゾビス（２−アミジノプロパン）二塩酸塩の１０重量％水溶液１０４．８部を添加し、溶液の温度を６０℃としたところ重合が開始した。２０時間後に、生成した高粘度の液体を取り出し、メタノール中に投入し、ポリマーを沈降せしめた。このものを４０℃の減圧乾燥機中で２日間乾燥し、ポリ−Ｎ−ビニルホルムアミドを得た。こうして得られたポリ−Ｎ−ビニルホルムアミドを１０重量％水溶液として４２８７．３部、および純水３９２５．３部、水酸化ナトリウム３６２部を混合せしめ、攪拌下、溶液の温度を７５℃とした。６時間後、この溶液に対して６Ｎ塩酸を攪拌下に添加し、塩酸塩とした後、この溶液をメタノール中に投入し、ポリマーを沈降せしめた。このものを５０℃の減圧乾燥機中で１日間乾燥し、ポリビニルアミン塩酸塩を得た。次いでポリビニルアミン塩酸塩を水酸化ナトリウム水溶液中に溶解せしめることでポリビニルアミン水溶液を得た。
【００７２】
得られた１０％濃度のポリビニルアミン水溶液を１８２ｇ／分の供給速度で供給しつつ、架橋剤としてのエチレングリコールジグリシジルエーテル（商品名：デナコールＥＸ−８１０、ナガセ化成工業株式会社製）を２．７３ｇ／分の供給速度で、内容量１．２リットルでジャケット付きのＫＲＣニーダー（株式会社栗本鐵工所社製）内に連続的に供給した。この時のＫＲＣニーダーの回転数は５３ｒｐｍであり、ジャケット内の温度は８０℃であった。ＫＲＣニーダー内を通過することにより、そのせん断力により架橋反応の進行と同時に細分化が行われ、本発明の塩基性吸水性樹脂（１２）が連続的に排出された。得られた本発明の塩基性吸水性樹脂（１２）の可溶性成分量は０．２％で、吸水倍率は１８．０ｇ／ｇで、乾燥後の粒子サイズ１０〜１０００μｍの粒子は８２重量％で、平均粒子サイズは５４０μｍであった。乾燥後の本発明の塩基性吸水性樹脂（１２）中の１０〜１０００μｍの粒子は、１０００μｍ〜８５０μｍの粒子を２９％、８５０μｍ〜５００μｍの粒子を２５％、５００μｍ〜３００μｍの粒子を１８％、３００μｍ〜１５０μｍの粒子を１３％、１５０μｍ〜１０μｍの粒子を１５％含んでいた。
（実施例３０）
実施例２９で得られた本発明の塩基性吸水性樹脂（１２）１００部を１００００部の純水で１日間水洗し、続いて４０℃の減圧乾燥機中で２日間乾燥した。このものを卓上粉砕機で粉砕せしめ、８５０μｍ以下の粒子として、本発明の塩基性吸水性樹脂（１３）を得た。
（実施例３１）
実施例２９において得られた本発明の塩基性吸水性樹脂（１２）８８３部と、参考例１で得られた酸性吸水性樹脂（１）１００部をニーダー中で攪拌下に混合し、両者の混合物を得た。混合物を８０℃の熱風乾燥機中で１時間乾燥し、更に乾燥物１００部にシリカ微粒子（商品名：レオロシールＱＳ−２０、株式会社トクヤマ製）０．３部を混合した後、卓上粉砕機で粉砕した。粉砕物を目開き８５０μｍの金網を通過せしめ、通過物を分取して本発明の吸水剤（１７）を得た。本発明の吸水剤（１７）は加圧下の吸水倍率が、測定開始から１時間後は２０．７ｇ／ｇで、４時間後は２３．６ｇ／ｇであった。
（実施例３２）
実施例３０において得られた本発明の塩基性吸水性樹脂（１３）５０部と、参考例１で得られた酸性吸水性樹脂（１）５０部とをドライブレンドし、本発明の吸水剤（１８）を得た。本発明の吸水剤（１８）は加圧下の吸水倍率が、測定開始から１時間後は２９．４ｇ／ｇで、４時間後は３７．３ｇ／ｇであった。
（実施例３３）
内容量１．２Ｌでジャケット付きのＫＲＣニーダー（（株）栗本鉄工所製）を用い、１分間に、樹脂固形分１００％のポリエチレンイミン（（株）日本触媒製、商品名「エポミンＳＰ−２００」）３２．７部に架橋剤としてエチレングリコールジグリシジルエーテル（ナガセ化成工業（株）製、商品名「デナコールＥＸ−８１０」）３．２７部を添加したものと、参考例１で得られた酸性吸水性樹脂（１）４４部とを、回転数５３ｒｐｍで攪拌しながら、ＫＲＣニーダーを通過させた。次いで、得られた通過物に、シリカ微粒子（（株）トクヤマ製、商品名「レオロシールＱＳ−２０」）０．２３部をブレンドして、本発明の吸水剤（１９）を得た。得られた吸水剤（１９）の塩水に対する加圧下吸水倍率は、測定開始から１時間後は３３．０ｇ／ｇであり、４時間後は３９．５ｇ／ｇであった。
【００７３】
【発明の効果】
本発明の塩基性吸水性樹脂の製法では、架橋反応の進行と同時に細分化が行われるため、塩基性吸水性樹脂内部の架橋密度分布がより均質となり、その結果、粒子サイズが揃うと同時に、吸水倍率に優れ、可溶性成分の少ないという特徴を有する塩基性吸水性樹脂を生産性良く製造することができる。
従って、本発明の方法で得られた塩基性吸水性樹脂は、酸性吸水性樹脂と混合される場合に最適な品質の塩基性吸水性樹脂とすることができるのみならず、同時に最適な粒度にサイズ調整することが可能である。
このため、本発明の方法で得られた塩基性吸水性樹脂は、酸性吸水性樹脂と混合されて吸水剤となったとき、この吸水剤は、加圧下の吸水倍率に著しく優れる高品質の吸水剤となっている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a basic water-absorbent resin, a method for producing a water-absorbing agent, and use thereof.
[0002]
More specifically, the present invention relates to a method for producing a water-absorbing agent having a significantly improved water absorption capacity under pressure and a method for producing a basic water-absorbing resin as a main component thereof.
[0003]
[Prior art]
In recent years, so-called water-absorbing resins have been widely used as sanitary materials such as paper diapers, sanitary napkins, and so-called incontinence pads for the purpose of absorbing body fluids.
[0004]
Examples of the water-absorbing resin include a crosslinked polyacrylic acid partially neutralized product, a hydrolyzate of starch-acrylic acid graft polymer, a saponified vinyl acetate-acrylic ester copolymer, an acrylonitrile copolymer, or an acrylamide. A hydrolyzate of a copolymer or a cross-linked product of these is known.
However, almost all of these conventionally known water-absorbing resins are obtained by neutralizing the acidic group of the acidic water-absorbing resin with an alkali metal compound or the like. For this reason, in the case where the vicinity of the particle surface is not subjected to secondary crosslinking treatment, the absorption capacity under pressure with respect to the physiological saline is less than 10 g / g, even if the vicinity of the particle surface is subjected to secondary crosslinking treatment. Even if it exists, the absorption capacity under pressure for artificial urine is at most 30 g / g, which is still insufficient to be used for disposable diapers and sanitary products, and it can absorb and swell a lot of artificial urine even under pressure conditions. A water-absorbing agent was envied.
In order to solve such problems, WO96 / 15180, WO96 / 17681, WO98 / 24832, WO98 / 37149, WO99 / 34841, WO99 / 34842, WO99 / 34843 In the publication, WO99 / 25393, WO99 / 30751, etc., a water-absorbing agent composed of an acidic water-absorbing resin and a basic water-absorbing resin is proposed. However, in the methods described in these patents, the basic water-absorbing resin as the main component of the water-absorbing agent is once finely granulated after passing through a lump gel state, and if necessary, the basic water-absorbing resin is sized to an optimum particle size. After adjustment, it is further mixed with acidic water-absorbing resin, and in large-scale production, very large lump gel must be handled, not only the equipment becomes large, but the productivity is very low, In addition, the quality of each batch had to be unstable. In particular, when the hydrated gel is mechanically subdivided after the lump gel is formed once, the network formed by cross-linking must be cut once, in which case the soluble components increase or the cross-linked structure However, there were problems such as non-uniformity and a large amount of energy required for fragmentation. EP 949290 A2 proposes a method of performing a crosslinking reaction in a suspension state of a basic resin. However, since an organic solvent is used, a process for removing the organic solvent is necessary, and the production equipment is Not only was it big, but productivity was very low. In addition, the basic water-absorbing resin obtained in this manner is substantially spherical, and irregularly shaped particles cannot be obtained.
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described conventional problems, and its purpose is to provide a basic water-absorbing resin as a main component of a water-absorbing agent excellent in water absorption capacity under pressure, 1) preferably in one step. 2) To provide a method of manufacturing a small equipment, 3) inexpensively, 4) a stable and high quality product, and 5) with high productivity. Another object is to provide a method for producing a water-absorbing agent with excellent water absorption capacity under pressure, 1) small equipment, 2) low cost, 3) stable high quality, and 4) high productivity. There is to do. Furthermore, when the water-absorbing agent obtained by the method of the present invention is used as a component of an absorbent article such as a diaper, leakage can be significantly reduced even when used for a long time, and the surface is in a dry state. Can be kept in. Further, the water-absorbing agent obtained by the method of the present invention can also be used as a component of a deodorizing product excellent in deodorizing ammonia, acetaldehyde, mercaptan and the like.
[0006]
[Means for Solving the Problems]
The inventors of the present application have arrived at the present invention as a result of intensive studies on a method for producing a novel basic water-absorbing resin and a method for producing a water-absorbing agent that can achieve the above-mentioned object.
That is, the present invention is water-soluble.Contains amino groupWhen a basic water-absorbing resin having a water absorption ratio of 1 g / g or more is obtained by reacting a basic resin with a cross-linking agent, the gel-like reactant obtained in the course of the cross-linking reaction is subdivided into particles. This is a process for producing an amorphous water-absorbing resin having an indefinite shape, which is characterized in that
The method for producing a water-absorbing agent according to the present invention is a method in which an acidic water-absorbing resin is mixed with the basic water-absorbing resin obtained by the above method.
Another method for producing a water-absorbing agent according to the present invention is to obtain a mixture of a basic water-absorbing resin and an acidic water-absorbing resin by allowing the acidic water-absorbing resin to coexist when performing the crosslinking reaction and fragmentation by the above method. Is the method.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
[0008]
In the present invention, the basic water-absorbing resin is a basic water-absorbing resin that is basic in pure water and is crosslinked to the extent that it can absorb and swell pure water. In the present invention, the basic water-absorbent resin that exhibits basicity in water preferably has a pH value of greater than 8, for example, in pure water, and the absorption rate of pure water is preferably 1 g / g or more. As a basic water-absorbing resin showing such physical property values, for example, it contains a basic group, and 50% to 100 mol% of the basic group exists in the form of an unneutralized (free) base and is insoluble in water. Mention may be made of basic resins which are loosely crosslinked until. More preferably, 70 to 100 mol% of the basic group is present in the form of an unneutralized (free) base, and most preferably 90 to 100 mol% of the basic group is an unneutralized (free) base. The basic resin is present in the form of and is loosely crosslinked until water insoluble. The basic water-absorbing resin more preferably used in the present invention contains a primary to quaternary amino group (amine group), and 50% to 100 mol% of the amino group (amine group) is unneutralized (free). The basic water-absorbing resin obtained by loosely crosslinking the amino group-containing basic resin present in the form of a base with a crosslinking agent until it becomes water-insoluble and water-swellable.
[0009]
Examples of the basic resin used in the present invention include water-soluble or water-dispersible, non-crosslinked hydrophilic basic resins that are substantially in a state before crosslinking. Such as, for example, linear polyalkyleneamine, branched polyalkyleneamine, polyvinylamine, polyallylamine, polyN-vinylimidazole, polyvinylpyridine, polyvinylpyridineamine oxide, polydiallylamine, polyamide polyamine, polydimethyl Aminoalkyl acrylate, polydimethylaminoalkyl methacrylate, polydimethylaminoalkyl acrylamide, polydimethylaminoalkyl methacrylamide, polyamidine, polyvinyl guanidine, polydiallylamine, hydrazine polyacrylate, aspartic acid-hexamethylenediamine polycondensate; such as polylysine Examples include basic polyamino acids; basic resins derived from natural products such as chitosan; and copolymers of these polymers. Can do. It is essential that these can be converted into a basic water-absorbent resin by crosslinking. Preferably, the basic resin is an amino group-containing basic resin, more preferably the basic resin is present in the form of 90 to 100 mol% of the basic group in an unneutralized (free) base, At least one selected from the group consisting of polyethyleneimine, polyallylamine, polyvinylamine, polydiallylamine, and polydiallyldimethylamine, and most preferably at least one selected from polyethyleneimine, polyallylamine, and polyvinylamine. In the present invention, the average molecular weight of the basic resin before crosslinking is preferably in the range of about 1,000 to 10,000,000.
[0010]
In the present invention, the basic water-absorbing resin is cross-linked with a cross-linking agent having two or more groups capable of reacting with the corresponding basic resin with its functional group (for example, an amino group (amine group)) to form a covalent bond, It can be obtained by introducing a crosslinked structure into the resin. As the crosslinking agent, when the functional group is an amino group (amine group), for example, an epoxy group, an aldehyde group, a halogenated alkyl group, an isocyanate group, a carboxyl group, an acid anhydride group, an acid halide group, an ester bond Conventionally used compounds having two or more moieties and active double bonds per molecule can be used. Examples of such crosslinking agents include bisepoxy compounds; dihalides such as epichlorohydrin and dibromoethylene; dialdehyde compounds such as formalin and glyoxal; diglycidyl ethers of (poly) ethylene glycols, (poly) propylene glycol Diglycidyl ethers, diglycidyl ethers of dialcohols such as neopentyl alcohol, polyglycidyl ethers of glycerol; α, β-unsaturated carboxylic esters such as methyl acrylate and ethyl acrylate; -Α, β-unsaturated carbonyl compounds; α, ω-alkylene diisocyanates and the like, but are not limited thereto. The type and amount of the crosslinking agent are selected in consideration of the water absorption capacity, strength, etc. of the basic water-absorbing resin to be obtained. When the basic resin is an amino group-containing basic resin, a polymeric amine The range of 0.001-20 mol% with respect to the unit is preferred. When the amount of the crosslinking agent is less than 0.001 mol%, the water absorption capacity of the basic water-absorbing resin obtained is low and the strength is insufficient, and when it exceeds 20 mol%, the water absorption capacity may be greatly reduced. is there.
[0011]
The method for producing the basic water-absorbent resin of the present invention is characterized in that shearing force is applied to the basic resin and the crosslinking agent, and the fragmentation is performed simultaneously with the progress of the crosslinking reaction. The fragmentation as used in the present invention means that the gel generated by crosslinking is finely crushed into a particulate size having fluidity. By applying a shearing force to the basic resin and the crosslinking agent, the basic resin and the crosslinking agent come into contact with each other, and the basic resin is crosslinked by the crosslinking agent. A uniform cross-linked structure is introduced into the gel-like basic water-absorbing resin obtained simultaneously with the progress of the cross-linking reaction, and at the same time, it is fragmented into particles. By performing fragmentation simultaneously with the progress of the cross-linking reaction, the cross-link density distribution in the basic water-absorbent resin particles that are produced individually becomes more uniform, and as a result, the particle size is uniform and at the same time the water absorption ratio is excellent and soluble. Basic water-absorbing resin particles having a feature of few components can be produced with high productivity. This is a feature that could not be achieved by the conventional method of fragmenting after the formation of a bulk gel, and it was subdivided simultaneously with the progress of the crosslinking reaction, so that the basic water-absorbent resin most suitable for the water-absorbing agent of the present invention. Can be obtained. Prior to fragmentation simultaneously with the progress of the crosslinking reaction, the basic resin and the crosslinking agent may be supplied in a state diluted with a solution or in an undiluted liquid state, respectively.
[0012]
In the present invention, the basic resin and the crosslinking agent may be supplied after being previously mixed in a solution state or a liquid state, respectively. An aqueous liquid is preferably used as a medium when mixed in a solution state. The total concentration in the mixed state of the basic resin and the crosslinking agent is preferably an aqueous liquid state having a concentration of 40% by weight or more, more preferably an aqueous liquid concentration of 80% by weight or more. The most preferred form for proper crosslink density distribution and particle control is that both are premixed in an undiluted liquid state. It is more preferable that the two are mixed in advance in a highly concentrated state as much as possible (for example, both are in an undiluted state) because a basic water-absorbent resin having a uniform crosslink density distribution can be obtained with good productivity. As long as both are in contact with each other under the situation where turbulent flow is generated, the mixing machine may not be used, and both may be mixed in a container exemplified below. Preferably, both are mixed in an in-pipe fluid mixer such as a line mill equipped with a device that actively generates turbulence. Examples of the in-tube fluid mixer include conventionally known devices such as a static in-tube mixing device and a mixing device having a liquid shearing mechanism. Examples of the static type in-pipe mixing device include Noritake static mixer (Noritake Co., Ltd.), Sulzer mixer (Sumitomo Heavy Industries, Ltd.), Toray static type in-pipe mixer (Toray Corp.), Skaya mixer ( Sakura Mfg. Co., Ltd.), TK-ROSS-LPD mixer (Special Machine Industries Co., Ltd.) and the like, and examples of the mixing device equipped with a liquid shearing mechanism include a homomixer and a homogenizer. .
[0013]
In the present invention, the basic resin and the cross-linking agent are subjected to shearing force and are subdivided simultaneously with the progress of the cross-linking reaction to become the basic water-absorbing resin of the present invention. In another embodiment, the basic resin and the cross-linking agent are fragmented simultaneously with the progress of the cross-linking reaction by shearing force in the container, and further discontinuously discharged out of the container and the basic water-absorbing resin of the present invention. Become. In still another embodiment, the basic resin and the cross-linking agent are continuously supplied into a container having a rotary stirring shaft, and the fragmentation is performed simultaneously with the progress of the crosslinking reaction by the shearing force generated by the stirring shaft. The basic water-absorbent resin of the present invention is discharged continuously. Examples of reaction vessels that can be sheared and subdivided simultaneously with the progress of the crosslinking reaction include, for example, a cylindrical mixer, a turbulator, a nauter mixer, a V mixer, a paddle dryer, an extruder, and a twin. Conventionally known containers such as arm type kneaders, Banbury mixers, screw type mixers, universal mixers, twin screw extruders, rotary mixers, roll mixers and the like can be exemplified. Examples of the reaction vessel that can subdivide the basic resin and the crosslinking agent simultaneously with the progress of the crosslinking reaction by shearing force in the vessel and can be discontinuously discharged outside the vessel include, for example, a cylindrical mixer, Nauta Examples include a type mixer, a V-type mixer, a double-arm kneader, a Banbury mixer, a universal mixer, and preferably a double-arm kneader. A basic resin and a cross-linking agent are continuously supplied into a container having a rotating stirring shaft, and the shearing force by the stirring shaft is used to perform fragmentation simultaneously with the progress of the cross-linking reaction, and then continuously discharged out of the container. Examples of the reaction vessel that can be used include a KRC kneader, a turbulizer, a paddle dryer, an extruder, a screw-type mixer, a twin-screw extruder, and a continuous kneader. The temperature and reaction time for the crosslinking reaction are usually in the range of several seconds to several hours at a temperature of room temperature to 150 ° C., although depending on the combination of the basic resin and the crosslinking agent used. Preferably, it is in the range of several seconds to 1 hour at a temperature of 50 ° C. to 120 ° C. Especially when the operation is continuously performed, it is preferable to complete the crosslinking reaction within the residence time in the container, and the container is compact. In order to achieve this, it is preferable to select conditions such that the reaction is completed within a range of several seconds to 50 minutes at a temperature of 50 ° C to 120 ° C. Further, the reaction may be carried out in any state under reduced pressure, normal pressure or increased pressure. Further, when an aqueous liquid is used as the solvent, it is possible to carry out the reaction while simultaneously subdividing the crosslinking reaction and removing the aqueous liquid at the same time.
[0014]
In the present invention, the basic water-absorbing resin thus obtained can be made into a desired basic water-absorbing resin through a granulation step, a washing step and / or a drying step, if necessary. It is also possible to control the degree of fragmentation and particle size of the basic water-absorbent resin obtained by controlling the rotation speed of the stirring shaft and the shape of the stirring blade.
[0015]
The basic water-absorbent resin of the present invention thus obtained has, for example, an indefinite shape, and the particle size is such that at least 80% by weight or more of the total particles have a particle size of 10 to 1000 μm, and is a water-soluble component. The amount is less than 10% by weight, and the water absorption ratio is in the range of 1 to 100 g / g. The basic water-absorbing resin of the present invention having such physical properties can be used as the water-absorbing agent of the present invention having excellent water absorption capacity under pressure by being further mixed with the acidic water-absorbing resin. In particular, in order to be mixed with an acidic water-absorbing resin and used as a water-absorbing agent, the average particle size of the basic water-absorbing resin is 100 to 850 μm (preferably 200 to 300 μm), and the amount of soluble components is less than 5% by weight, It is preferable that the water absorption ratio is controlled in the range of 5 to 20 g / g.
[0016]
In the present invention, the acidic water-absorbing resin is an acidic water-absorbing resin that has been crosslinked to the extent that it is acidic in pure water and can absorb and swell pure water. In the present invention, the acidic water-absorbing resin that exhibits acidity in water preferably has, for example, a pH lower than 6 in pure water, and preferably has a water absorption ratio of 1 g / g or more (more preferably). The water absorption capacity of pure water is 10 g / g or more). As an acidic water-absorbing resin exhibiting such physical property values, for example, it contains an acidic group, and 50% to 100 mol% of the acidic group is present in the form of an unneutralized (free) acid and becomes loose until it is insoluble in water. Mention may be made of cross-linked acidic resins. More preferably 70 to 100 mol% of the acidic groups are present in the form of unneutralized (free) acid, most preferably 90 to 100 mol% of the acidic groups are in the form of unneutralized (free) acid. And is a cross-linked acidic resin that is loosely crosslinked until water insoluble. Examples of the acidic water-absorbing resin more preferably used in the present invention include an acidic water-absorbing resin containing at least one acid group selected from the group consisting of a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group. it can. In the present invention, the acidic water-absorbing resin is, for example, a) a method of polymerizing a polymerizable monomer containing an acid group in the presence of a copolymerizable crosslinking agent, or b) a polymerizable monomer containing an acid group. It can be obtained by a conventionally known method such as a method of subjecting the acid group-containing polymer obtained by polymerization to a post-crosslinking treatment. The acidic water-absorbing resin that can be used in the present invention may be a cross-linked polypeptide such as a cross-linked polyaspartic acid or polyglutamic acid cross-linked product or a natural product-derived acidic water-absorbing resin such as a cross-linked carboxymethyl cellulose. .
[0017]
Post-crosslinking treatment of the acid group-containing polymer is, for example, I) a method of introducing a crosslinked structure by heat treatment, II) a method of introducing a crosslinked structure by irradiation with an electron beam, gamma ray or the like, III) polyethylene glycol diglycidyl 2 functional groups that can react with functional groups of acid group-containing polymers such as ether, glycerol diglycidyl ether, ethylene glycol, polyethylene glycol, propylene glycol, glycerin, pentaerythritol, ethylenediamine, polyethyleneimine, and ethylene carbonate in one molecule. This can be achieved by, for example, a method of introducing a crosslinked structure into the polymer with a compound having at least one.
[0018]
The method for producing an acidic water-absorbing resin that is more preferably employed in the present invention is based on the ease of control of the degree of polymerization and the degree of cross-linking. It is a method of polymerizing in the presence.
[0019]
Examples of the polymerizable monomer containing an acid group that can be suitably used in the present invention include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, and their Polymerizable monomers containing carboxylic acid groups such as anhydrides; vinyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, vinyl toluene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, 2- ( Polymerizable monomers containing a sulfonic acid group such as (meth) acryloylethanesulfonic acid and 2- (meth) acryloylpropanesulfonic acid; 2-hydroxyethylacryloyl phosphate, 2-hydroxyethylmethacryloyl phosphate, phenyl-2-acryloyl Contains phosphate groups such as loxyethyl phosphate and vinyl phosphate And a polymerizable monomer.
[0020]
Of these, preferred are polymerizable monomers containing carboxylic acid groups or sulfonic acid groups, and particularly preferred are polymerizable monomers containing carboxylic acid groups, most preferably acrylic acid. . These monomers containing an acid group may be used alone or in combination of two or more.
[0021]
In the present invention, if necessary, other polymerizable monomers can be used together with the monomer containing an acid group. Examples of such compounds include unsaturated carboxylic acids (acrylic acid, methacrylic acid, ethacrylic) such as methyl (meth) acrylate, ethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and polyethylene glycol mono (meth) acrylate. Alkyl, alkylene oxide esters of acid, crotonic acid, sorbic acid, maleic acid, itaconic acid, cinnamic acid, etc .; aromatic vinyl hydrocarbons such as styrene; aliphatic vinyl hydrocarbons such as ethylene, propylene, butene; acrylonitrile And unsaturated amides such as acrylamide and methacrylamide.
[0022]
Examples of the copolymerizable crosslinking agent that can be copolymerized with a monomer containing an acid group that can be suitably used in the present invention include the compound (1) having at least two polymerizable double bonds and at least one polymerizable two-bonding agent. Examples thereof include compound (2) having a heavy bond and having at least one functional group reactive with the monomer.
[0023]
Specific examples of the compound (1) include the following. For example, N, N′-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meta) ) Acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, triallylcia Nurate, triallyl isocyanurate, triallyl phosphate, triallylamine, poly (meth) allyloxyalkane, divinylbenzene, divinyltoluene, divinyloxy Emissions, divinyl naphthalene, divinyl ether, divinyl ketone, trivinylbenzene, tolylene diisocyanate, hexamethylene diisocyanate.
[0024]
Examples of the compound (2) include a compound having an epoxy group and a polymerizable double bond in one molecule such as glycidyl (meth) acrylate; a hydroxy group in one molecule such as N-methylol (meth) acrylamide. And a compound having a polymerizable double bond; N, N, N-trimethyl-N- (meth) acryloyloxyethyltrimethylammonium chloride, N, N, N-triethyl-N- (meth) acrylooxyethyltrimethylammonium Examples thereof include chlorides, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, allylamine, and unsaturated compounds containing a quaternary amino group such as vinylpyridine.
[0025]
Among the copolymerizable cross-linking agents, bis (meth) acrylamide, di- or poly-esters of polyols and unsaturated monocarboxylic acids, and polyallyl compounds are preferable, and N, N'-methylene is particularly preferable. It is at least one selected from bisacrylamide, trimethylolpropane tri (meth) acrylate, (poly) ethylene glycol diacrylate, triallylamine, and poly (meth) allyloxyalkane.
[0026]
In the present invention, the amount of the copolymerizable crosslinking agent is usually 0.001 to 10%, preferably 0.01 to 5%, based on the total weight of all the polymerizable monomers and the copolymerizable crosslinking agent. If the amount of the copolymerizable cross-linking agent is less than 0.001%, the obtained acidic water-absorbent resin may have a low gel strength upon water absorption, and if it exceeds 10%, the water absorption ratio may decrease. .
[0027]
The amount of the other polymerizable monomer used as necessary is usually 40% or less, preferably 20% or less, based on the total weight of all the polymerizable monomers and the copolymerizable crosslinking agent.
[0028]
In the polymerization, starch and cellulose, starch and cellulose derivatives, polyvinyl alcohol, polyacrylic acid, polyacrylic acid cross-linked hydrophilic polymer, and hypophosphorous acid (salt) chain A transfer agent or a water-soluble or water-dispersible surfactant may be added. The compounds added to these polymerizable monomers include U.S. Pat. Nos. 4,076,663, 4,320,040, 4,833,222, 5,118,719, 5,149,750, 5,154,713, and 5,264,495, and European Patents 0372981, and 4,496,594. It is illustrated in the issue.
[0029]
In the present invention, the polymerization method of the acid group-containing monomer, or the polymerization method of the acid group-containing monomer and the copolymerizable cross-linking agent and other polymerizable monomers used as necessary includes, for example, bulk polymerization and Although precipitation polymerization can be employed, it is preferable to perform aqueous solution polymerization or reverse phase suspension polymerization using the monomer as an aqueous solution from the viewpoint of performance and ease of control of polymerization. Further, as the solvent in this case, for example, water, methanol, ethanol, acetone, N, N-dimethylformamide, dimethyl sulfoxide, methyl ethyl ketone, or a mixture of two or more thereof may be used. The concentration of the acid group-containing monomer when a solvent is used is not particularly limited, but is usually 10% or more, preferably 15 to 80% on a weight basis. The polymerization temperature is usually in the range of 0 to 150 ° C, preferably 10 to 100 ° C.
[0030]
In addition, as a method for initiating polymerization, a conventionally known method may be used, and examples thereof include a method of polymerizing using a radical polymerization catalyst and a method of irradiating with radiation, electron beam, ultraviolet rays and the like.
[0031]
In the method using a radical polymerization catalyst, examples of the catalyst include inorganic peroxides such as potassium persulfate, ammonium persulfate, and sodium persulfate; t-butyl hydroperoxide, hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide, and the like. And organic peroxides such as 2,2′-azobis (2-amidinopropane) dihydrochloride, azoisobutyronitrile, azobiscyanovaleric acid and the like. When an oxidizing radical polymerization catalyst such as peroxide is used, redox polymerization may be performed using a reducing agent such as sodium sulfite, sodium hydrogen sulfite, ferrous sulfate, L-ascorbic acid in combination. A plurality of these radical polymerization catalysts may be used in combination. The amount of the radical polymerization catalyst used may be normal, for example, usually 0.0005 to 5%, preferably 0.0001 to 1% based on the total weight of all polymerizable monomers and copolymerizable crosslinking agent.
[0032]
In the present invention, the acidic water-absorbing resin obtained by the above-described method is used in a substantially dry powder state through a conventionally known drying / pulverization / classification step, if necessary. Preferably, the acidic water-absorbing resin is mixed with the basic water-absorbing resin in the form of a powder having a water content of less than 20% by weight and a particle size in the range of 10 to 1000 μm to form the water-absorbing agent of the present invention. be able to. When the water content of the acidic water-absorbing resin is 20% by weight or more, care should be taken because the desalting effect of the water-absorbing agent may be lowered depending on the mixing conditions with the basic water-absorbing resin.
The method for producing a water-absorbing agent of the present invention is a method in which a basic water-absorbing resin obtained by performing fragmentation of a basic resin and a cross-linking agent simultaneously with the progress of the cross-linking reaction and an acidic water-absorbing resin are mixed. Specific examples of this production method include the following methods (a) and (b).
(A) A basic water-absorbing resin and an acidic water-absorbing resin, which are obtained by subdividing the reaction product into a basic resin and a cross-linking agent simultaneously with the progress of the cross-linking reaction, are separately prepared in advance, and then both are mixed.
(B) When the reaction product is subdivided simultaneously with the progress of the cross-linking reaction between the basic resin and the cross-linking agent, by coexisting with the acidic water-absorbing resin, Mix with acidic water-absorbing resin.
In the above method (a), the mixing ratio of the basic water-absorbing resin and the acidic water-absorbing resin varies depending on the purpose of use and the type of liquid to be absorbed, but is 95: 5 to 5: by weight ratio (as solid content). A range of 95 is preferable, and a range of 90:10 to 10:90 is more preferable. The mixing of the basic water-absorbing resin and the acidic water-absorbing resin is not particularly limited as long as the two can be mixed. Examples of such a mixing apparatus include a cylindrical rotary mixer, a double mixer, and the like. Wall-conical mixer, V-shaped mixer, ribbon-type mixer, screw-type mixer, fluid-type furnace rotary desk-type mixer, airflow-type mixer, double-armed kneader, internal mixer, rotary mixer, Conventionally known mixers such as shear type mixers, turbulizers, universal mixers, Nauter type mixers, fluidized bed type mixers and the like can be exemplified. In addition, the basic water-absorbing resin and the acid water-absorbing resin may be obtained by subjecting each particle to surface cross-linking treatment before mixing.
In the method (b), as the basic resin and the crosslinking agent, the basic resin and the crosslinking agent described above are used, and the basic resin is preferably 50% to 100 mol% of the basic group. Is present in the form of an unneutralized (free) base, more preferably 70-100 mol% of the basic group is present in the form of an unneutralized (free) base, most preferably the basic group Is present in the form of an unneutralized (free) base. The concentration of the basic resin used is preferably 50% by weight or more, more preferably 80% by weight or more, and most preferably 98% by weight or more.
When the basic resin is an amino group-containing basic resin, the amount of the crosslinking agent used in the method (b) is preferably in the range of 0.001 to 20 mol% with respect to the polymeric amine unit. Further, the mixing ratio of the basic resin and the acidic water-absorbing resin is preferably in the range of 90:10 to 10:90, more preferably in the range of 80:20 to 20:80, in terms of weight ratio (as solid content). Preferably it is the range of 70: 30-30: 70.
The water content of the acidic water-absorbing resin used in the method (b) is preferably less than 20% by weight.
The mixing of the basic resin, the cross-linking agent, and the acidic water-absorbing resin is not particularly limited as long as the three can be mixed. Examples of such a mixing apparatus include a KRC kneader, a turbulizer, and a paddle. Examples thereof include a dryer, an extruder, a screw type mixer, a twin screw extruder, and a continuous kneader. The temperature and reaction time during the crosslinking reaction are usually in the range of several seconds to several hours at a temperature of room temperature to 150 ° C. Preferably, it is in the range of several seconds to 1 hour at a temperature of 50 ° C. to 120 ° C. Especially when the operation is continuously performed, it is preferable to complete the crosslinking reaction within the residence time in the container, and the container is compact. In order to achieve this, it is preferable to select conditions such that the reaction is completed within a range of several seconds to 50 minutes at a temperature of 50 ° C to 120 ° C. Further, the reaction may be carried out in any state under reduced pressure, normal pressure or increased pressure.
Compared with the method (a), the method (b) does not isolate the basic water-absorbing resin obtained by the crosslinking reaction of the basic resin and the crosslinking agent, so that the water-absorbing agent can be produced with higher productivity in one step. it can.
Thus, the water-absorbing agent obtained by the production method of the present invention can be dried if necessary and pulverized to obtain a water-absorbing agent having a desired particle size. The drying temperature in the case of drying is, for example, in the range of 50 to 200 ° C., and in some cases, drying may be performed in an inert gas atmosphere such as nitrogen. Examples of dryers include hot air dryers, rotary dryers, paddle dryers, disc dryers, belt dryers, J-Nauter dryers, high-frequency dryers, vacuum dryers, freeze dryers, and grooved mixers. Examples include a dryer, a rotary dryer, a disk dryer, a fluidized bed dryer, an airflow dryer, and an infrared dryer. Further, the pulverization method is not particularly limited, and usual devices such as a hammer pulverizer, an impact pulverizer, a roll pulverizer, and a jet airflow pulverizer can be used.
The water absorption capacity under pressure of the water-absorbing agent obtained by the production method of the present invention (after 1 hour from the start of measurement) is preferably 20 g / g or more, more preferably 30 g / g or more, and most preferably 35 g / g or more. . The water absorption capacity under pressure of the water absorbing agent (after 4 hours from the start of measurement) is preferably 25 g / g or more, more preferably 35 g / g or more, and most preferably 40 g / g or more.
The average particle size of the water-absorbing agent obtained by the production method of the present invention is preferably 10 to 1000 μm, more preferably 100 to 850 μm, and most preferably 200 to 600 μm.
In the present invention, a disinfectant, a deodorant, an antibacterial agent, a fragrance, various inorganic powders, an organic powder, a foaming agent, a pigment, a dye, a hydrophilic fiber, a filler, a hydrophobic fiber, a fertilizer, and the like are further added during kneading. Thus, various functions can be imparted to the water-absorbing agent obtained by the production method of the present invention.
The water-absorbing agent obtained by the production method of the present invention can be particularly suitably used for various absorbent articles, in particular, absorbent bodies such as paper diapers, sanitary napkins and incontinence pads that are becoming thinner, and have been used for a long time. Even in such a case, it is possible to provide an absorbent article that can remarkably reduce leakage and can keep the surface smooth and dry.
[0033]
Since the water-absorbing agent obtained by the production method of the present invention can absorb salt water quickly, various absorbent articles; water-absorbing materials such as paper diapers, sanitary napkins, incontinence pads, and hygiene materials such as water-absorbing agents for wipers; freshness Food field such as retention agent, meat and seafood drip absorbents; agricultural and horticultural field such as water retention agent for plants and soil, water retention agent for slope revegetation; building material field such as paint additive and anti-condensation agent; Communication field such as water solution, water sealant for submarine cable; information field such as surface coating agent for printing film; industrial field such as water-containing coagulant; household goods such as disposable warmers and desiccant mainly composed of calcium chloride Field: It can be suitably used in a wide range of fields such as civil engineering fields such as civil engineering sealants and concrete admixtures.
[0034]
Furthermore, the water-absorbing agent obtained by the production method of the present invention has the effect of removing unpleasant odorous substances such as ammonia, acetaldehyde and mercaptans alone, and is effective as a component of a deodorizing product.
[0035]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these. In addition, the amount of soluble components in the basic water-absorbent resin, the water absorption ratio of the basic water-absorbent resin, the water absorption ratio under pressure of the water-absorbing agent, and the water content of the acidic water-absorbent resin were measured by the following methods. In the following, “parts” and “%” simply represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.
[0036]
(A) Amount of soluble component of basic water-absorbent resin
A basic water-absorbent resin (Wa [g]) in an amount corresponding to 1 g as a solid content was accurately measured to 0.0001 g, poured into 200 g of pure water, stirred for 16 hours, and the mixed solution was filtered with a filter paper (ADVANTEC). Product, No. 2), and the filtrate was collected. A filtrate in an amount corresponding to 1 to 3 mg of amine component dissolved in a 200 ml beaker was collected (Wb [g]), and purified water was added to 50 g, and 0.1 mol / l hydrochloric acid was further added thereto to adjust the pH. Was adjusted to 1-2. After adding a few drops of toluidine blue to the solution, a 1/400 mol / l polyvinyl potassium sulfate solution (PVSK, for colloidal titration) was dropped, and the end point (T [ml ]). Calculation of the amount of soluble components of the basic water-absorbing resin was determined by the following equation.
[0037]
[Expression 1]
(B) Water absorption ratio of basic water-absorbing resin and acidic water-absorbing resin
A basic water-absorbing resin (or acidic water-absorbing resin) in an amount equivalent to 0.2 g as a solid content is accurately measured up to 0.0001 g and placed in a non-woven bag (60 mm × 60 mm) and immersed in 100 g of pure water. did. After 24 hours, the bag is pulled up and 250G (250 × 9.81 m / s 2 ) For 3 minutes, and then the weight Wc (g) of the bag was measured. The same operation was performed without using a basic water absorbent resin (or acidic water absorbent resin), and the weight Wd (g) at that time was measured. From these weights Wc, Wd,
Water absorption magnification (g / g) = (Wc−Wd) /0.2−1
The water absorption capacity (g / g) of the basic water absorbent resin (or acidic water absorbent resin) was calculated according to
[0039]
(C) Water absorption magnification under pressure of water absorbent
0.9g of a water absorbent is uniformly sprayed on the bottom mesh of a plastic support cylinder with an inner diameter of 60mm fused with a stainless steel 400 mesh wire mesh (mesh size 38µm) on the bottom. On the other hand, a piston that is adjusted so that a load of 4.9 kPa can be applied uniformly, has an outer diameter slightly smaller than 60 mm, does not cause a gap on the wall surface with the support cylinder, and does not hinder vertical movement. Loads were placed in this order, and the weight of this set of measuring devices was measured (We).
[0040]
A glass filter with a diameter of 90 mm is placed inside a 150 mm Petri dish, and brine (2.0 g of potassium chloride, 2.0 g of sodium sulfate, 0.85 g of ammonium dihydrogen phosphate, 0.15 g of diammonium hydrogen phosphate, calcium chloride 2 Deionized water for dissolution is added to 0.25 g of hydrate and 0.5 g of magnesium chloride hexahydrate to give a total weight of 1000 g) so as to be at the same level as the surface of the glass filter. A filter paper having a diameter of 90 mm is placed thereon so that the entire surface is wetted, and excess liquid is removed.
[0041]
The above measuring device set is placed on the wet filter paper and the liquid is absorbed under load. After the water absorbing agent absorbs the liquid for a predetermined time, the measuring device set is lifted and its weight is measured again (Wf). The value obtained by subtracting We from Wf was divided by the weight of the water-absorbing agent (0.9 g) to determine the water absorption capacity (g / g) under pressure. The above measurement is performed with the piston and the load on, and after the weight measurement, the measuring device set is placed on the wet filter paper again, and salt water is absorbed under the load until the next predetermined time, and this operation is repeated until the unit The water absorption magnification under pressure after time was determined.
[0042]
(D) Water content of acidic water-absorbing resin
The initial weight (Wg) of the acidic water-absorbent resin is measured in advance, and the weight (Wh) after drying for 3 hours in a hot air dryer at 180 ° C. is measured. The value obtained by subtracting Wh from Wg and dividing by Wg was expressed as a percentage to obtain the water content (%) of the acidic water-absorbent resin.
[0043]
(Reference Example 1)
1008.8 parts of acrylic acid, 8.63 parts of N, N′-methylenebisacrylamide as a copolymerizable cross-linking agent, and 3960.9 parts of pure water are mixed, degassed with nitrogen gas for 60 minutes, and then opened and closed. The reaction system was charged with nitrogen and kept under a nitrogen atmosphere while maintaining the liquid temperature at 20 ° C. Then, under stirring, 30.5 parts of a 10% by weight aqueous solution of 2,2'-azobis (2-amidinopropane) dihydrochloride, 10.8 parts of a 10% by weight aqueous solution of hydrogen peroxide and 1% by weight of L-ascorbic acid When 25.2 parts of each aqueous solution was added, polymerization started after 5 minutes, and the reaction system reached the peak temperature after 30 minutes. 30 minutes after the polymerization temperature reached its peak, the produced hydrogel crosslinked polymer was taken out and passed through a meat chopper to obtain a hydrogel crosslinked polymer that was fragmented. This was dried in a 130 ° C. hot air dryer for 1 hour. The dried product was pulverized with a roll granulator (manufactured by Nippon Granulator Co., Ltd.), the pulverized product was passed through a wire mesh with an opening of 850 μm, and the passed product was separated to obtain an acidic water-absorbing resin (1). In addition, the water content of this obtained acidic water-absorbing resin (1) was 6%, and the water absorption rate with respect to pure water was 14 g / g.
[0044]
(Reference Example 2)
A mixture of 800 parts of acrylic acid, 1150 parts of a 50% by weight aqueous solution of 2-acrylamido-2-methylpropanesulfonic acid, 5.35 parts of N, N'-methylenebisacrylamide as a crosslinking agent, and 2930 parts of pure water was mixed. After degassing with gas for 60 minutes, the reaction system was charged into an openable / closable sealed container, and nitrogen substitution of the reaction system was continued while maintaining the liquid temperature at 20 ° C. in a nitrogen atmosphere. Then, with stirring, 30.3 parts of a 10% by weight aqueous solution of 2,2'-azobis (2-amidinopropane) dihydrochloride, 33.3 parts of a 3% by weight aqueous solution of hydrogen peroxide and 0.5% of L-ascorbic acid When 50 parts by weight of aqueous solution was added, polymerization started after 1 minute, and the reaction system reached the peak temperature after 17 minutes. 30 minutes after the polymerization temperature reached its peak, the produced hydrogel crosslinked polymer was taken out and passed through a meat chopper to obtain a hydrogel crosslinked polymer that was fragmented. This was dried in a hot air dryer at 60 ° C. for 1 hour, and further dried in a vacuum dryer at 60 ° C. for 3 hours. The dried product was pulverized with a roll granulator (manufactured by Nippon Granulator Co., Ltd.), the pulverized product was passed through a wire mesh with an opening of 850 μm, and the passed product was separated to obtain an acidic water-absorbing resin (2). The water content of the obtained acidic water-absorbing resin (2) was 15%.
[0045]
Example 1
Ethylene glycol diglycidyl ether (trade name: Denacol) as a cross-linking agent for 100% polyethyleneimine (trade name: Epomin SP-200, manufactured by Nippon Shokubai Co., Ltd.) supplied at a feed rate of 72.7 g / min. The mixture was continuously obtained by supplying EX-810 (manufactured by Nagase Kasei Kogyo Co., Ltd., solid content 100%) at a supply rate of 7.3 g / min. At the same time, the mixture is continuously fed into a KRC kneader (made by Kurimoto Steel Co., Ltd.) having a two-axis rotating shaft that drives at a rotational speed of 53 rpm and having an internal capacity of 1.2 liters. The inside was continuously passed through and subjected to fragmentation simultaneously with the cross-linking reaction by shearing force to obtain the basic water-absorbent resin (1) of the present invention continuously. At this time, the temperature of water passing through the jacket was 80 ° C. The basic water-absorbent resin (1) of the present invention has a soluble component amount of 3.4%, a water absorption ratio of 6.5 g / g, and particles having a particle size of 10 to 1000 μm are 98% by weight. The size was 270 μm. In the basic water-absorbent resin (1) of the present invention, 10 to 1000 μm particles are 1000 to 850 μm particles 6%, 850 μm to 500 μm particles 14%, 500 μm to 300 μm particles 22%, 300 μm to 150 μm. It contained 43% particles and 15% 150 μm to 10 μm particles.
[0046]
(Example 2)
30% polyethyleneimine (trade name: Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) in a reaction vessel with a lid on a jacketed double-arm kneader with a jacket having an internal volume of 10 liters and two sigma-type stirring blades ) While adding 5000 g, stirring at a rotation speed of 40 rpm, 1597 g of N, N′-methylenebisacrylamide 9.4% aqueous solution (temperature 80 ° C.) was added, and fragmentation was performed simultaneously with the crosslinking reaction under shear force. . At this time, the jacket temperature was 60 ° C. The finely divided gel was discharged from the kneader 3 minutes after the start of the reaction in the kneader, and then passed through a dome gran (manufactured by Fuji Paudal Co., Ltd.) to obtain the basic water-absorbing resin (2) of the present invention. . The basic water-absorbent resin (2) of the present invention has a soluble component amount of 3.1%, a water absorption ratio of 9.5 g / g, and particles having a particle size of 10 to 1000 μm after drying are 98% by weight, The average particle size was 210 μm. Further, 10 to 1000 μm particles in the basic water-absorbing resin (2) after drying are 7% of particles of 850 μm to 500 μm, 22% of particles of 500 μm to 300 μm, 43% of particles of 300 μm to 150 μm, and 150 μm. It contained 28% of 10 μm particles.
[0047]
(Example 3)
A basic water absorbent resin (3) of the present invention was obtained in the same manner as in Example 2 except that the jacket temperature of Example 2 was 25 ° C. and the reaction time in the kneader was 10 minutes. The basic water-absorbing resin (3) of the present invention has a soluble component amount of 3.4%, a water absorption ratio of 9.7 g / g, and particles having a particle size of 10 to 1000 μm after drying are 99% by weight, The average particle size was 230 μm. In addition, 10 to 1000 μm particles in the basic water-absorbing resin (3) after drying are 9% of particles of 850 μm to 500 μm, 25% of particles of 500 μm to 300 μm, 40% of particles of 300 μm to 150 μm, and 150 μm. It contained 26% of 10 μm particles.
[0048]
Example 4
In Example 2, the basic water-absorbent resin (4) of the present invention was used in the same manner as in Example 2 except that instead of the dome granule, a meat chopper having a reversal prevention member spirally provided in the meat chopper casing was used. ) The basic water-absorbent resin (4) of the present invention has a soluble component amount of 3.2%, a water absorption ratio of 9.5 g / g, and particles having a particle size of 10 to 1000 μm after drying are 93% by weight, The average particle size was 165 μm. In addition, 10 to 1000 μm particles in the basic water-absorbing resin (4) after drying are 13% of 1000 to 850 μm particles, 7% of particles of 850 μm to 500 μm, 9% of particles of 500 μm to 300 μm, and 300 μm. It contained 25% of ~ 150 μm particles and 46% of 150-10 μm particles.
[0049]
(Example 5)
N, N′-methylenebisacrylamide (temperature: 80 ° C.) as a crosslinking agent for polyethyleneimine (trade name: Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd.) with a concentration of 30% supplied at a supply rate of 182 g / min. 9.4% aqueous solution) at a feed rate of 58 g / min, and a two-axis rotating shaft that drives both at a rotational speed of 53 rpm, with an internal capacity of 1.2 liters and a jacketed KRC kneader (Co., Ltd.) Kurimoto Steel Works Co., Ltd.), continuously passing through the KRC kneader, and performing fragmentation at the same time as the cross-linking reaction by shearing force, continuously the basic water-absorbing resin (5) of the present invention Obtained. At this time, the temperature of water passing through the jacket was 80 ° C. The obtained basic water-absorbing resin (5) of the present invention has a soluble component amount of 3.5%, a water absorption ratio of 10.4 g / g, and 84% by weight of particles having a particle size of 10 to 1000 μm after drying. The average particle size was 650 μm. In addition, 10 to 1000 μm particles in the basic water absorbent resin (5) after drying are 34% of 1000 to 850 μm particles, 31% of particles of 850 μm to 500 μm, 22% of particles of 500 μm to 300 μm, and 300 μm. It contained 11% of ~ 150 μm particles and 2% of 150-10 μm particles.
[0050]
(Example 6)
N, N′-methylenebisacrylamide (temperature 80 ° C.) as a crosslinking agent for polyethyleneimine having a concentration of 50% (trade name: Epomin P-1050, manufactured by Nippon Shokubai Co., Ltd.) supplied at a supply rate of 157 g / min. 9.4% aqueous solution) at a feed rate of 83 g / min, and a two-axis rotating shaft that drives both at a rotational speed of 53 rpm, with an internal capacity of 1.2 liters and a jacketed KRC kneader (Co., Ltd.) Kurimoto Steel Works Co., Ltd.), continuously passing through the KRC kneader, and performing fragmentation at the same time as the cross-linking reaction by shearing force, continuously the basic water-absorbing resin (6) of the present invention Obtained. At this time, the temperature of water passing through the jacket was 80 ° C. The basic water-absorbent resin (6) of the present invention has a soluble component amount of 4.7%, a water absorption ratio of 8.0 g / g, and particles having a particle size of 10 to 1000 μm after drying are 88% by weight. The average particle size was 290 μm. Further, the 10-1000 μm particles in the basic water-absorbing resin (6) after drying are 21% 1000-850 μm particles, 12% 850 μm-500 μm particles, 16% 500 μm-300 μm particles, 300 μm. It contained 35% ˜150 μm particles and 16% 150˜10 μm particles.
[0051]
(Example 7)
N, N′-methylenebisacrylamide (9. Temperature 80 ° C.) as a cross-linking agent for polyethyleneimine (trade name: Lupasol-P, manufactured by BASF) with a concentration of 50% supplied at a supply rate of 157 g / min. 4% aqueous solution) at a feed rate of 58 g / min and a KRC kneader with a capacity of 1.2 liters and a jacket that has both shafts driven at a rotational speed of 53 rpm (Kurimoto Corporation) The product is continuously fed into the KRC kneader and subjected to fragmentation at the same time as the crosslinking reaction by shearing force to continuously obtain the basic water-absorbent resin (7) of the present invention. It was. At this time, the temperature of water passing through the jacket was 80 ° C. The basic water-absorbent resin (7) of the present invention has a soluble component amount of 4.3%, a water absorption ratio of 7.3 g / g, and particles having a particle size of 10 to 1000 μm after drying are 88% by weight. The average particle size was 305 μm. Further, 10 to 1000 μm particles in the basic water absorbent resin (7) after drying are 19% of 1000 to 850 μm particles, 18% of particles of 850 μm to 500 μm, 14% of particles of 500 μm to 300 μm, and 300 μm. It contained 29% of ~ 150 μm particles and 20% of 150-10 μm particles.
[0052]
(Example 8)
In Example 1, the same procedure as in Example 1 was carried out except that the supply amount of ethylene glycol diglycidyl ether (trade name: Denacol EX-810, manufactured by Nagase Kasei Kogyo Co., Ltd.) as the crosslinking agent was changed to 5.5 g / min. The basic water-absorbent resin (8) of the present invention was obtained. The basic water-absorbent resin (8) of the present invention has a soluble component amount of 4.6%, a water absorption ratio of 11.1 g / g, a particle size of 10 to 1000 μm is 95% by weight, and the average particle size is 310 μm. there were. In the basic water-absorbent resin (8) of the present invention, 10-1000 μm particles are 1000-850 μm particles 8%, 850 μm-500 μm particles 18%, 500 μm-300 μm particles 27%, 300 μm-150 μm. It contained 29% particles and 18% 150-10 μm particles.
[0053]
Example 9
Ethylene glycol diglycidyl ether (trade name: Denacol EX-810) as a crosslinking agent for polyethyleneimine (trade name: Lupasol-WF, manufactured by BASF) having a concentration of 100% fed at a feed rate of 72.7 g / min. , Manufactured by Nagase Kasei Kogyo Co., Ltd., solid content 100%) at a feed rate of 7.3 g / min, a mixture was continuously obtained. At the same time, the mixture is continuously fed into a KRC kneader (made by Kurimoto Steel Co., Ltd.) having a two-axis rotating shaft that drives at a rotational speed of 53 rpm and having an internal capacity of 1.2 liters. The inside was continuously passed through and subjected to fragmentation at the same time as the crosslinking reaction by shearing force, thereby continuously obtaining the basic water-absorbent resin (9) of the present invention. At this time, the temperature of water passing through the jacket was 80 ° C. The basic water-absorbent resin (9) of the present invention has a soluble component amount of 3.5%, a water absorption ratio of 5.2 g / g, and particles having a particle size of 10 to 1000 μm are 98% by weight, and average particles The size was 275 μm. In the basic water-absorbent resin (9) of the present invention, 10 to 1000 μm particles are 1000% to 850 μm particles, 3%, 850 μm to 500 μm particles are 16%, 500 μm to 300 μm particles are 25%, and 300 μm to 150 μm. It contained 38% particles and 18% 150 μm to 10 μm particles.
[0054]
(Example 10)
In Example 1, in place of ethylene glycol diglycidyl ether which is a crosslinking agent, methyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was supplied at 3.7 g / min. The basic water-absorbing resin (10) of the invention was obtained. The basic water-absorbent resin (10) of the present invention has a soluble component amount of 2.7%, a water absorption ratio of 2.4 g / g, a particle size of 10 to 1000 μm, 99% by weight, and an average particle size of 265 μm. Met. The particles of 10 to 1000 μm in the basic water-absorbent resin (10) of the present invention are 1% of 1000 to 850 μm particles, 17% of particles of 850 μm to 500 μm, 27% of particles of 500 μm to 300 μm, and 300 μm to 150 μm. And 28% of particles and 27% of particles of 150 to 10 μm.
[0055]
(Example 11)
The basic water-absorbent resin of the present invention was used in the same manner as in Example 10 except that ethyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.) was supplied at 3.7 g / min instead of methyl acrylate in Example 10. (11) was obtained. The basic water-absorbent resin (11) of the present invention has a soluble component amount of 3.5%, a water absorption ratio of 3.4 g / g, a particle size of 10 to 1000 μm, 96% by weight, and an average particle size of 305 μm. Met. The particles of 10 to 1000 μm in the basic water-absorbing resin (11) of the present invention are 3% of 1000 to 850 μm particles, 20% of particles of 850 μm to 500 μm, 29% of particles of 500 μm to 300 μm, and 300 μm to 150 μm. And 33% of particles and 15% of particles of 150 to 10 μm.
[0056]
Example 12
40 parts of the basic water-absorbing resin (1) obtained in Example 1, 60 parts of the acidic water-absorbing resin (1) obtained in Reference Example 1, and silica fine particles (trade name: Leolosil QS-20, Tokuyama Corporation) 0.3 parts) was dry blended to obtain the water-absorbing agent (1) of the present invention. The water absorbing agent (1) had a water absorption capacity under pressure of 36.7 g / g after 1 hour from the start of measurement and 42.5 g / g after 4 hours.
[0057]
(Example 13)
100 parts of the basic water-absorbent resin (2) obtained in Example 2 and 37.5 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 were mixed with stirring in a kneader, and a mixture of the two. Got. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour, and further mixed with 100 parts of a dried product, 0.3 parts of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Corporation), and then a solid grinder. (VM27-S, manufactured by Orient). The pulverized product was passed through a wire mesh having an opening of 850 μm, and the passed product was separated to obtain the water-absorbing agent (2) of the present invention. The water absorbing agent (2) had a water absorption capacity under pressure of 37.9 g / g after 1 hour from the start of measurement and 43.9 g / g after 4 hours.
[0058]
(Example 14)
100 parts of the basic water-absorbent resin (2) obtained in Example 2 and 58.3 parts of the acidic water-absorbent resin (2) obtained in Reference Example 2 were mixed with stirring in a kneader, and a mixture of the two. Got. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour, and further mixed with 100 parts of a dried product, 0.3 parts of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Corporation), and then a solid grinder. (VM27-S, manufactured by Orient). The pulverized product was passed through a metal mesh having an opening of 850 μm, and the passed product was collected to obtain the water-absorbing agent (3) of the present invention. The water absorbing agent (3) had a water absorption capacity under pressure of 39.0 g / g after 1 hour from the start of measurement and 40.5 g / g after 4 hours.
[0059]
(Example 15)
In Example 13, the water-absorbing agent (4) of the present invention was obtained in the same manner as in Example 13, except that the silica fine particles mixed before pulverization by the vertical pulverizer were added to the mixture before hot air drying at 80 ° C. Got. The water absorbing agent (4) had a water absorption capacity under pressure of 35.8 g / g after 1 hour from the start of measurement and 42.7 g / g after 4 hours.
[0060]
(Example 16)
In Example 13, the mixing of the basic water-absorbent resin (2) and the acidic water-absorbent resin (1) obtained in Reference Example 1 was performed except that a turbulizer (manufactured by Hosokawa Micron Corporation) was used instead of the kneader. In the same manner as in Example 13, the water-absorbing agent (5) of the present invention was obtained. The water absorbing agent (5) had a water absorption capacity under pressure of 37.6 g / g after 1 hour from the start of measurement and 43.7 g / g after 4 hours.
[0061]
(Example 17)
Using the basic water-absorbing resin (3) obtained in Example 3, it was mixed with the acidic water-absorbing resin (1) in the same manner as in Example 13, followed by drying, pulverization and fractionation. Agent (6) was obtained. The water absorbing agent (6) had a water absorption capacity under pressure of 36.3 g / g after 1 hour from the start of measurement and 42.6 g / g after 4 hours.
(Example 18)
Using the basic water-absorbing resin (4) obtained in Example 4, it was mixed with the acidic water-absorbing resin (1) in the same manner as in Example 13, followed by drying, pulverization and fractionation. Agent (7) was obtained. The water absorbing agent (7) had a water absorption capacity under pressure of 36.5 g / g after 1 hour from the start of measurement and 43.0 g / g after 4 hours.
[0062]
(Example 19)
12075 parts of the basic water-absorbent resin (4) obtained in Example 4 and 3935 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 were mixed with a high-speed shear mixer (cyclomix , Manufactured by Hosokawa Micron Co., Ltd.) under stirring to obtain a mixture of the two. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour, and further mixed with 100 parts of a dried product, 0.3 parts of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Corporation), and then a solid grinder. (VM27-S, manufactured by Orient). The pulverized material was passed through a wire mesh having an opening of 850 μm, and the passing material was separated to obtain the water-absorbing agent (8) of the present invention. The water-absorbing agent (8) of the present invention had a water absorption capacity under pressure of 37.0 g / g after 1 hour from the start of measurement and 43.5 g / g after 4 hours.
[0063]
(Example 20)
100 parts of the basic water-absorbent resin (5) obtained in Example 5 and 37.5 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 were mixed with stirring in a kneader. Obtained. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour. Further, 0.3 part of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Co., Ltd.) was mixed with 100 parts of the dried product. Crushed. The pulverized product was passed through a wire mesh having an opening of 850 μm, and the passed product was collected to obtain the water-absorbing agent (9) of the present invention. The water-absorbing agent (9) of the present invention had a water absorption capacity under pressure of 36.7 g / g after 1 hour from the start of measurement and 42.5 g / g after 4 hours.
[0064]
(Example 21)
100 parts of the basic water absorbent resin (5) obtained in Example 5 and 37.5 parts of the acidic water absorbent resin (1) obtained in Reference Example 1 were stirred in a kneader to obtain a mixture of both. . After adding 0.21 part of silica fine particles to 100 parts of this mixture and drying for 15 minutes in a fluidized bed dryer (manufactured by Yamato Kagaku Co., Ltd., Parvis mini bed GA22 type) at 80 ° C., a table grinder Crushed. The pulverized material was passed through a wire mesh having an opening of 850 μm, and the passing material was separated to obtain the water-absorbing agent (10) of the present invention. The water-absorbing agent (10) of the present invention had a water absorption capacity under pressure of 36.5 g / g after 1 hour from the start of measurement and 42.6 g / g after 4 hours.
[0065]
(Example 22)
100 parts of the basic water absorbent resin (6) of the present invention obtained in Example 6 and 53.85 parts of the acidic water absorbent resin (1) obtained in Reference Example 1 were mixed with stirring in a kneader. A mixture of both was obtained. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour. Further, 0.3 part of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Co., Ltd.) was mixed with 100 parts of the dried product. Crushed. The pulverized product was passed through a wire mesh having an opening of 850 μm, and the passed product was collected to obtain the water-absorbing agent (11) of the present invention. The water-absorbing agent (11) of the present invention had a water absorption capacity under pressure of 37.4 g / g after 1 hour from the start of measurement and 44.0 g / g after 4 hours.
[0066]
(Example 23)
Instead of 100 parts of the basic water-absorbing resin (6) of the present invention, the acidic water-absorbing resin was obtained in the same manner as in Example 22 by using the basic water-absorbing resin (7) of the present invention obtained in Example 7. After mixing with (1), drying, pulverization and fractionation were performed to obtain the water-absorbing agent (12) of the present invention. The water-absorbing agent (12) of the present invention had a water absorption capacity under pressure of 36.3 g / g after 1 hour from the start of measurement and 42.7 g / g after 4 hours.
[0067]
(Example 24)
40 parts of the basic water-absorbent resin (8) obtained in Example 8, 60 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 and 0.3 part of silica fine particles were dry-blended. A water absorbing agent (13) was obtained. The water-absorbing agent (13) of the present invention had a water absorption capacity under pressure of 30.2 g / g after 1 hour from the start of measurement and 38.3 g / g after 4 hours.
[0068]
(Example 25)
40 parts of the basic water-absorbent resin (9) obtained in Example 9, 60 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 and 0.3 part of silica fine particles were dry-blended. A water absorbing agent (14) was obtained. The water-absorbing agent (14) of the present invention had a water absorption capacity under pressure of 31.5 g / g after 1 hour from the start of measurement and 40.1 g / g after 4 hours.
[0069]
(Example 26)
40 parts of the basic water-absorbent resin (10) obtained in Example 10, 60 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 and 0.3 part of silica fine particles were dry-blended. A water absorbing agent (15) was obtained. The water-absorbing agent (15) of the present invention had a water absorption capacity under pressure of 30.7 g / g after 1 hour from the start of measurement and 39.9 g / g after 4 hours.
[0070]
(Example 27)
40 parts of the basic water absorbent resin (11) obtained in Example 11, 60 parts of the acidic water absorbent resin (1) obtained in Reference Example 1 and 0.3 part of silica fine particles were dry blended, and A water absorbing agent (16) was obtained. The water-absorbing agent (16) of the present invention had a water absorption capacity under pressure of 32.1 g / g after 1 hour from the start of measurement and 41.1 g / g after 4 hours.
(Comparative Example 1)
Ethylene glycol diglycidyl ether (trade name: Denacol EX-810, Nagase Kasei Kogyo Co., Ltd.) for a polyethyleneimine aqueous solution (trade name: Epomin P-1000, manufactured by Nippon Shokubai Co., Ltd., diluted with water) diluted to 10% 1.5 mol%) was added and reacted at 60 ° C. for 16 hours to obtain a comparative basic water-absorbing resin (1). The obtained bulk comparative basic water-absorbing resin (1) was previously finely crushed using an extruder, and 37.4 parts (as a solid content) of this and the acidic water-absorbing resin (1) obtained in Reference Example 1 were obtained. 56.1 parts were mixed, and the resulting mixture was further passed through a meat chopper twice to obtain a kneaded mixture of both. The obtained kneaded product is dried in a hot air dryer at 80 ° C. for 2 hours, and then the dried product is pulverized using a table pulverizer, and the pulverized product is passed through a wire mesh with an opening of 850 μm, and the passing product is collected. Thus, a comparative water absorbing agent (1) was obtained. The water absorption capacity under pressure of the comparative water-absorbing agent (1) was 17.5 g / g 1 hour after the start of measurement and 24.9 g / g after 4 hours.
(Example 28)
The deodorizing effect of the water-absorbing agent (1) of the present invention obtained in Example 1 was quantified by the following method. In a 500 cc sealed container, 1 g of the water-absorbing agent (1) of the present invention was added to 20 g of physiological saline (0.9% saline) containing 1% of ammonia to cause gelation. The amount of ammonia in the head space in the container after 1 hour had dropped to 37% or less of the blank (when the water-absorbing agent of the present invention was not added). In a 500 cc sealed container, 1 g of the water-absorbing agent (1) of the present invention was added to 20 g of physiological saline (0.9% saline) containing 1% acetaldehyde to cause gelation. The amount of acetaldehyde in the head space in the container after 1 hour had dropped to 10% or less of the blank (when the water-absorbing agent of the present invention was not added). From this result, it was found that the water-absorbing agent of the present invention has an effect of removing ammonia and acetaldehyde.
[0071]
(Example 29)
After mixing 3500 parts of N-vinylformamide (manufactured by Aldrich) and 13900 parts of pure water, degassing with nitrogen gas for 60 minutes, charging into an openable and shuttable container, keeping the liquid temperature at 20 ° C. under nitrogen atmosphere The nitrogen substitution of the reaction system was continued. Next, 104.8 parts of a 10% by weight aqueous solution of 2,2′-azobis (2-amidinopropane) dihydrochloride was added with stirring, and the temperature of the solution was adjusted to 60 ° C., and polymerization started. After 20 hours, the produced high-viscosity liquid was taken out and poured into methanol to precipitate the polymer. This was dried in a vacuum dryer at 40 ° C. for 2 days to obtain poly-N-vinylformamide. 4287.3 parts of the poly-N-vinylformamide thus obtained as a 10% by weight aqueous solution, 3925.3 parts of pure water and 362 parts of sodium hydroxide were mixed, and the temperature of the solution was adjusted to 75 ° C. with stirring. After 6 hours, 6N hydrochloric acid was added to the solution with stirring to obtain a hydrochloride, and the solution was put into methanol to precipitate the polymer. This was dried in a vacuum dryer at 50 ° C. for 1 day to obtain polyvinylamine hydrochloride. Subsequently, polyvinylamine hydrochloride was dissolved in an aqueous sodium hydroxide solution to obtain an aqueous polyvinylamine solution.
[0072]
1. While supplying the obtained polyvinylamine aqueous solution having a concentration of 10% at a supply rate of 182 g / min, ethylene glycol diglycidyl ether (trade name: Denacol EX-810, manufactured by Nagase Kasei Kogyo Co., Ltd.) as a cross-linking agent is used. It was continuously fed into a KRC kneader (manufactured by Kurimoto Seiko Co., Ltd.) with an internal capacity of 1.2 liters and a jacket at a feeding rate of 73 g / min. At this time, the rotation speed of the KRC kneader was 53 rpm, and the temperature in the jacket was 80 ° C. By passing through the inside of the KRC kneader, the shearing force caused fragmentation to occur simultaneously with the progress of the crosslinking reaction, and the basic water-absorbent resin (12) of the present invention was continuously discharged. The basic water-absorbent resin (12) of the present invention has a soluble component amount of 0.2%, a water absorption ratio of 18.0 g / g, and particles having a particle size of 10 to 1000 μm after drying are 82% by weight. The average particle size was 540 μm. The 10-1000 μm particles in the basic water-absorbent resin (12) of the present invention after drying are composed of 29% of particles of 1000 μm to 850 μm, 25% of particles of 850 μm to 500 μm, 18% of particles of 500 μm to 300 μm, It contained 13% of particles of 300 μm to 150 μm and 15% of particles of 150 μm to 10 μm.
(Example 30)
100 parts of the basic water-absorbing resin (12) of the present invention obtained in Example 29 was washed with 10,000 parts of pure water for 1 day, and then dried in a vacuum dryer at 40 ° C. for 2 days. This was pulverized with a desktop pulverizer to obtain the basic water-absorbent resin (13) of the present invention as particles of 850 μm or less.
(Example 31)
883 parts of the basic water absorbent resin (12) of the present invention obtained in Example 29 and 100 parts of the acidic water absorbent resin (1) obtained in Reference Example 1 were mixed with stirring in a kneader. A mixture was obtained. The mixture was dried in a hot air dryer at 80 ° C. for 1 hour. Further, 0.3 part of silica fine particles (trade name: Leolosil QS-20, manufactured by Tokuyama Co., Ltd.) was mixed with 100 parts of the dried product. Crushed. The pulverized material was passed through a wire mesh having an opening of 850 μm, and the passing material was separated to obtain the water-absorbing agent (17) of the present invention. The water-absorbing agent (17) of the present invention had a water absorption capacity under pressure of 20.7 g / g after 1 hour from the start of measurement and 23.6 g / g after 4 hours.
(Example 32)
50 parts of the basic water-absorbent resin (13) of the present invention obtained in Example 30 and 50 parts of the acidic water-absorbent resin (1) obtained in Reference Example 1 were dry blended, and the water-absorbing agent of the present invention ( 18) was obtained. The water-absorbing agent (18) of the present invention had a water absorption capacity under pressure of 29.4 g / g after 1 hour from the start of measurement and 37.3 g / g after 4 hours.
(Example 33)
Using a KRC kneader with an internal volume of 1.2 L and a jacket (manufactured by Kurimoto Iron Works Co., Ltd.), a polyethyleneimine having a resin solid content of 100% per minute (manufactured by Nippon Shokubai Co., Ltd., trade name “Epomin SP-200”) And 32.7 parts of ethylene glycol diglycidyl ether (manufactured by Nagase Kasei Kogyo Co., Ltd., trade name “Denacol EX-810”) as a crosslinking agent was added in 32.7 parts, and obtained in Reference Example 1. 44 parts of acidic water-absorbing resin (1) was passed through a KRC kneader while stirring at a rotation speed of 53 rpm. Next, 0.23 parts of silica fine particles (trade name “Leolosil QS-20” manufactured by Tokuyama Corporation) were blended with the obtained passing material to obtain the water-absorbing agent (19) of the present invention. The water absorption capacity under load of the obtained water-absorbing agent (19) with respect to salt water was 33.0 g / g after 1 hour from the start of measurement, and 39.5 g / g after 4 hours.
[0073]
【The invention's effect】
In the production method of the basic water absorbent resin of the present invention, since the fragmentation is performed simultaneously with the progress of the crosslinking reaction, the crosslink density distribution inside the basic water absorbent resin becomes more uniform, and as a result, the particle size is uniform, It is possible to produce a basic water-absorbing resin having excellent water absorption ratio and low soluble components with high productivity.
Therefore, the basic water-absorbing resin obtained by the method of the present invention can not only be a basic water-absorbing resin of optimum quality when mixed with an acidic water-absorbing resin, but also at the same time with an optimum particle size. It is possible to adjust the size.
For this reason, when the basic water-absorbing resin obtained by the method of the present invention is mixed with an acidic water-absorbing resin to become a water-absorbing agent, the water-absorbing agent is a high-quality water-absorbing material that is remarkably excellent in water-absorbing capacity under pressure. It is an agent.
Claims (13)
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| JP2000393864A JP4704559B2 (en) | 1999-12-27 | 2000-12-25 | Manufacturing method of basic water-absorbing resin, manufacturing method of water-absorbing agent, and use thereof |
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| JP2000393864A JP4704559B2 (en) | 1999-12-27 | 2000-12-25 | Manufacturing method of basic water-absorbing resin, manufacturing method of water-absorbing agent, and use thereof |
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| WO2002059214A1 (en) * | 2001-01-26 | 2002-08-01 | Nippon Shokubai Co., Ltd. | Water absorbing agent and method for production thereof, and water absorbing article |
| JP3987348B2 (en) * | 2001-01-26 | 2007-10-10 | 株式会社日本触媒 | Manufacturing method of water-absorbing agent |
| KR100697944B1 (en) * | 2003-02-10 | 2007-03-20 | 니폰 쇼쿠바이 컴파니 리미티드 | Water-absorbing agent |
| JP4824911B2 (en) * | 2004-01-30 | 2011-11-30 | 一般財団法人川村理化学研究所 | Hydrogel, cross-linked hydrogel and method for producing them |
| US8519058B2 (en) * | 2004-02-23 | 2013-08-27 | E I Du Pont De Nemours And Company | Crosslinked polymers containing biomass derived materials |
| JP5353114B2 (en) * | 2008-08-21 | 2013-11-27 | 日東紡績株式会社 | Allylamine cross-linked polymer and deodorant |
| KR102621646B1 (en) * | 2018-03-06 | 2024-01-05 | 닛산 가가쿠 가부시키가이샤 | Electroless plating agent containing polymer and metal particles |
| WO2019188669A1 (en) * | 2018-03-29 | 2019-10-03 | Ｓｄｐグローバル株式会社 | Water absorbent resin particles and production method therefor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10509915A (en) * | 1994-12-06 | 1998-09-29 | ザ、プロクター、エンド、ギャンブル、カンパニー | Absorbable material |
| JPH11302391A (en) * | 1998-02-18 | 1999-11-02 | Nippon Shokubai Co Ltd | Surface crosslinking of water absorptive resin |
| JPH11349689A (en) * | 1998-04-09 | 1999-12-21 | Nippon Shokubai Co Ltd | Crosslinked polymer particle and its preparation and use thereof |
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2000
- 2000-12-25 JP JP2000393864A patent/JP4704559B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH10509915A (en) * | 1994-12-06 | 1998-09-29 | ザ、プロクター、エンド、ギャンブル、カンパニー | Absorbable material |
| JPH11302391A (en) * | 1998-02-18 | 1999-11-02 | Nippon Shokubai Co Ltd | Surface crosslinking of water absorptive resin |
| JPH11349689A (en) * | 1998-04-09 | 1999-12-21 | Nippon Shokubai Co Ltd | Crosslinked polymer particle and its preparation and use thereof |
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| JP2001247683A (en) | 2001-09-11 |
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